MODIFICATION OF METALLIC SURFACES WITH PHOSPHONIC ACIDS

CROSS-REFERENCE

[0001] This application claims the benefit of U.S. Provisional Application No. 63/050,228, filed July 10, 2020, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Surface modification of a material may be used to achieve different interfacial properties of the material. For example, antibacterial layers, corrosion resistant layers, or anti -biofouling layers may be incorporated onto the surface of medical devices designed to be implanted in the body. Many chemistries exist for the covalent modification of various surfaces, but there are few methods known for the functionalization of platinum, gold, or other metallic surfaces, such as palladium, iridium, or rhodium. There exists a need for additional approaches to attach reagents and other functionalities to such metallic surfaces.

SUMMARY

[0003] Provided herein are reagents, methods, and compositions which fulfill a need for new and improved methods of functionalizing metallic surfaces, including platinum and gold surfaces. In some embodiments, the metallic surface is a platinum-group metal. In some embodiments, the reagents, methods, and compositions can be used to functionalize palladium, iridium, or rhodium surfaces. In some of the embodiments described herein, the reagents, methods and compositions can be used to add various functionalities onto metallic surfaces through the formation of a metallic phosphonate bond between a phosphonic acid or phosphonate ester and the metallic surface. In some embodiments, the phosphonic acid or phosphonate comprises a reactive group or capture moiety that enable the addition of further materials to the metallic surface, such as additional surface modification groups (e.g. hydrogels) or other functional moieties (e.g. binding agents such as peptides or oligonucleotides). In other embodiments, the phosphonic acid or phosphonate comprises the desired surface modification group (e.g. without the need for conducting another reaction to add the desired group). In some embodiments, the metallic surface is a platinum surface, or an oxide thereof. In some embodiments, the metallic surface is a gold surface, or an oxide thereof. In some embodiments, the metallic surface is a palladium surface, or an oxide thereof. In some embodiments, the metallic surface is an iridium surface, or an oxide thereof. In some embodiments, the metal surface is a rhodium surface, or an oxide thereof.

[0004] The reagents, methods and compositions of the present disclosure are especially suited to allow for precise control of the addition of various functionalities onto metallic surfaces, including platinum, gold, palladium, iridium, rhodium, or an oxide thereof. The materials provided herein allow for facile functionalization of the surfaces with a controlled amount of reagent that forms a stable bond with the metallic surface. The ease of synthesis, robustness of protocols for synthesis, and stability of metal phosphonate bonds allow for easy and controlled further functionalization of the surface. In some embodiments, this allows for robust protocols to be developed for addition of further surface functionalization groups in a manner that allows for control of fine characteristics. For example, hydrogels with finely tunable characteristics can be allowed to polymerize upon a metallic surface functionalized with the reagents provided herein. As the reagents and protocols provided herein yield predictable results, fine tuning of the hydrogel characteristics, such as density, thickness, cross-linking density, grafting density, functional groups, or conductivity, can be performed. Similar processes can be used to develop robust protocols for functionalization with any other surface modification group.

[0005] Also provided herein are hydrogel materials suitable for grafting on to metallic surfaces in order to prevent biofouling on the surface. Such hydrogels are particularly useful when deployed on electrodes and other electrokinetic devices that produce electric fields in proximity to biological samples, as the presence of a hydrogel layer can prevent destruction of the sample and accumulation of degraded sample on the electrode surface. In order for such a hydrogel layer to perform this function without interfering with the performance of the electric current on the sample, it is important that the hydrogel layer be constructed with certain fine characteristics (for example, density, thickness, and conductivity) which require precise control in making the hydrogel layer on the surface. Thus, there is a need for reagents which can functionalize surfaces and allow for controlled deposition of surface modification materials, including hydrogels. In addition to being applied to platinum, gold, palladium, iridium, or rhodium surfaces described herein, these hydrogels may also be linked to other metal surfaces capable of forming bonds with phosphonates, including without limitation silicon, aluminum, titanium, iron, zinc, zirconium, nickel, silver, copper, cobalt, or chromium.

[0006] In one aspect, provided herein, is a functionalized metallic surface comprising a metallic surface bound to a molecule having the structure: wherein

R is optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, or optionally substituted heteroaryl; and wherein the metallic surface comprises at least one metal selected from platinum, gold, palladium, iridium, and rhodium, an oxide thereof, or any combination thereof.

[0007] In some embodiments, R has the structure X-L-, wherein L is a linking moiety and X is a reactive handle or capture moiety, or R has the structure Y-L-, wherein L is a linking moiety and Y is a surface modification group. In some embodiments, L is an optionally substituted alkylene chain or optionally substituted heteroalkylene chain.

In some embodiments, L has the structure of formula:

-[Z-(CR ¹ R ² ) _n ] _m - wherein each R ¹ and R ² is independently H or optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl, or R ¹ and R ² on the same atom are taken together to form an oxo, or R ¹ s on adjacent atoms are taken together to form a double bond, or R ¹ s and R ² s on adjacent atoms are taken together to from a triple bond; each Z is independently absent, -O-, -NR ³ -, -S-, -SS-, -S(O)-, -S(O) ₂ -, -C(O)-, -C(O)O-, - C(O)NR ³ , -OC(O)O-, -NR ³ C(O)NR ³ -, -OC(O)NR ³ -, -S(O) ₂ O-, -S(O) ₂ NR ³ -, -OS(O) ₂ O-, -NR ³ SO ₂ NR ³ -, or -OSO ₂ NR ³ -; each R ³ is independently H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl; each n is independently an integer from 1 to 30; and m is an integer from 1 to 30. [0008] In some embodiments, L comprises a chain of one to one hundred atoms, wherein each atom in the chain is independently selected from C, N, O, S, Si, and P. In some embodiments, the first atom in the chain is C.

[0009] In some embodiments, L comprises one or more subunits selected from wherein each n is independently an integer from 1-30. In some embodiments, L comprises the structure: wherein each n is independently an integer from 1-30; and each p is independently an integer from

1-30.

[0010] In some embodiments, L comprises a polymer. In some embodiments, the polymer comprises a polyethylene, a polypropylene, a polyvinyl halide, a polystyrene, a nylon, a polyamide, a polyester, a polyaramide, a polyacrylate, a poly methacrylate, a poly tetrafluoroethylene, a polysaccharide, a poly(alkylene oxide), a poly(vinyl pyrrolidone), a poly(vinyl alcohol), a polyoxazoline, a poly(acryloylmorpholine), or any combination or derivative thereof.

[0011] In some embodiments, R has the structure X-L-. In some embodiments, X comprises a reactive functional group selected from an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, acid, activated ester, alkene, alcohol, halide, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, oxime, isocyanate, isothiocyanate, hydrazine, and hydrazide, or any combination thereof. In some embodiments, X has the structure:

X ¹ -L ^x -Z ^x - wherein Z ^x is a bond, -O-, -NR ⁴ -, -S-, -SS-, -S(O)-, S(O) ₂ -, -C(O)-, -C(O)O-, -C(O)NR ⁴ , - OC(O)O-, -NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, -S(O) ₂ O-, -S(O) ₂ NR ⁴ ., -OS(O) ₂ O-, - NR ⁴ S(O) ₂ NR ⁴ -, or -OS(O) ₂ NR ⁴ -;

L ^x is absent, optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted heteroalkylene, optionally substituted arylene, optionally substituted arylalkylene, optionally substituted heteroarylalkylene, optionally substituted arylheteroalkylene, or optionally substituted heteroarylheteroalkylene;

X ¹ comprises an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, carboxylic acid, activated ester, alkene, alcohol, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, oxime, isocyanate, isothiocyanate, hydrazine, or hydrazide; and each R ⁴ is independently H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl.

[0012] In some embodiments, wherein Z ^x is a bond, -O-, -C(O)-, -NR ⁴ -, -C(O)O-, or -C(O)NR ⁴ . In some embodiments, L ^x has the structure -(CR ⁵ R ⁶ ) _r -, wherein each R ⁵ and R ⁶ is independently H, halogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl, or R ⁵ and R ⁶ on the same atom are taken together to form an oxo, or R ⁵ s on adjacent atoms are taken together to form a double bond, or R ⁵ s and R ⁶ s on adjacent atoms are taken together to from a triple bond; and r is an integer from 0-30. In some embodiments, X ¹ comprises an amine, carboxylic acid, maleimide, azide, alkyne, halide, alkene, or sulfhydryl.

[0013] In some embodiments, X is wherein

R ⁵ and R ⁶ are each independently H or C ₁ -C ₃ alkyl; r is 0 or 1; and

X ¹ is azide, alkyne, halide, alkene, or sulfhydryl.

[0014] In some embodiments, X is In some embodiments, X comprises a capture moiety selected from biotin, avidin, streptavidin, a nucleic acid, a peptide, and a protein, or any combination thereof.

[0015] In one aspect, provided herein, is a kit comprising a functionalized metallic surface provided herein and instructions for use.

[0016] In some embodiments, R has the structure Y-L-. In some embodiments, Y comprises a surface modification group selected from hydrophobic residues, hydrophilic residues, charged residues, cationic residues, anionic residues, polysaccharides, hydrophobic polymers, hydrophilic polymers, antimicrobial agents, biological materials, biocompatibility materials, anti-fouling materials, conductivity materials, semi-conductive materials, heat resistant materials, anti-corrosive material, catalysts, and magnetic materials, or any combination thereof.

[0017] In some embodiments, Y has the structure Y ⁴ -L ^Y -Z ^y -, wherein Z ^Y is a bond, -O-, -NR ⁴ -, -S-, -SS-, -S(O)-, S(O) ₂ -, -C(O)-, -C(O)O-, -C(O)NR ⁴ , - OC(O)O-, -NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, -S(O) ₂ O-, -S(O) ₂ NR ⁴ ., -OS(O) ₂ O-, -NR ⁴ S(O) ₂ NR ⁴ - , -OS(O) ₂ NR ⁴ -, or reaction product formed by a covalent bond forming reaction between an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, carboxylic acid, activated ester, alkene, alcohol, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, oxime, isocyanate, isothiocyanate, hydrazine, or hydrazide and a suitable complementary reactive group;

L ^Y is absent, optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted heteroalkylene, optionally substituted arylene, optionally substituted arylalkylene, optionally substituted heteroarylalkylene, optionally substituted arylheteroalkylene, or optionally substituted heteroarylheteroalkylene;

Y ¹ comprises at least one surface modification residue; and each R ⁴ is independently H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl.

[0018] In some embodiments, Z ^Y is a bond, -O-, -NR ⁴ -, -S-, -SS-, -S(O)-, S(O) ₂ -, -C(O)-, - C(O)O-, -C(O)NR ⁴ -, -OC(O)O-, -NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, -S(O) ₂ O-, -S(O) ₂ NR ⁴ -, -OS(O) ₂ O-, -

NR ⁴ S(O) ₂ NR ⁴ -, -OS(O) ₂ NR ⁴ -,

In some embodiments, L ^Y is absent. In some embodiments,

Y ¹ comprises hydrophobic residues. In some embodiments, the hydrophobic residues comprise a hydrophobic polymer. In some embodiments, the hydrophobic polymer comprises polyethylene, polypropylene, polystyrene, polyvinylhalide, polytetrafluoroethylene, polymethylmethacrylate, polycarbonate, polyether-urethane, polydimethylsiloxane, or any combination or derivative thereof. In some embodiments, the hydrophobic residues comprise fatty acids or derivatives thereof.

[0019] In some embodiments, Y ¹ comprises hydrophilic residues. In some embodiments, the hydrophilic residues comprise a hydrophilic polymer. In some embodiments, the hydrophilic polymer comprises a polyacrylamide, a polyacrylate, a poly methacrylate, a poly(alkylene oxide), a poly(vinyl pyrrolidone), a poly(vinyl alcohol), a polyoxazoline, a poly(N-acryloyl morpholine), or any combination of derivative thereof. In some embodiments, the hydrophilic polymer comprises polyacrylamide, poly(diethyl acrylamide), poly(dimethyl acrylamide), poly(N-isopropylacrylamide), poly(acrylic acid), poly(methacrylic acid) poly(methyl acrylate), poly(ethyl acrylate), poly(2- hydroxyethyl acrylate), poly(propyl acrylate), poly(butyl acrylate), poly(methyl methacrylate), poly(2-hydroxyethyl methacrylate), poly(tetrahydrofurfuryl methacrylate), poly(ethylene oxide), poly(propylene oxide), poly(vinyl pyrrolidone), polyoxazoline, poly(2-ethyloxazoline), or poly(N- acryloyl morpholine).

[0020] In some embodiments, Y comprises the structure: wherein each R ⁷ is independently H, optionally substituted C ₁ -C ₃ alkyl or optionally substituted C ₁ -C ₃ hydroxy alkyl; each R ⁸ is independently H or C ₁ -C ₃ alkyl; each X ⁷ is independently absent, -O-, -S-, or -NR ⁹ ; each R ⁹ is independently H or C ₁ -C ₆ alkyl; and s is an integer from 1 to 10000.

[0021] In some embodiments, Y ¹ comprises cationic residues. In some embodiments, Y ¹ comprises a cationic polymer. In some embodiments, the cationic residues comprise protonated amine groups, protonated substituted amine groups, quaternary amine groups, or any combination thereof. In some embodiments, Y ¹ comprises anionic residues. In some embodiments, Y ¹ comprises an anionic polymer. In some embodiments, the anionic residues comprise carboxylates, sulfonates, sulfmates, phosphates, phosphonates, or any combination thereof.

[0022] In some embodiments, the surface modification group comprises hydrophobic residues, hydrophilic residues, charged residues, cationic residues, anionic residues, polysaccharides, hydrophobic polymers, hydrophilic polymers, antimicrobial agents, biological materials, biocompatibility materials, anti-fouling materials, conductivity materials, semi-conductive materials, heat resistant materials, anti-corrosive material, catalysts, magnetic materials, or any combination thereof. In some embodiments, the surface modification group comprises a hydrogel. In some embodiments, the hydrogel comprises an acrylate, a methacrylate, an acrylamide, or a methacrylamide, or any combination thereof. In some embodiments, the hydrogel has a thickness from about 0.001 micron to about 10 microns. In some embodiments, wherein the hydrogel has a conductivity from about 0.1 S/m to about 10 S/m.

[0023] In some embodiments, at least about 1%, at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the metallic surface is functionalized. In some embodiments, the metallic surface is at least partially oxidized. In some embodiments, at least about 1%, at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the metallic surface is oxidized.

[0024] In some embodiments, the metallic surface comprises a metal alloy. In some embodiments, the metal alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% of the metal by weight. In some embodiments, the metallic surface comprises the metal and an additional material. In some embodiments, the metal surface comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% of the metal or any oxide of the metal by weight. [0025] In some embodiments, the metal surface is configured to be placed inside the body of a mammal. In some embodiments, the metal surface is a surgical or dental implant. In some embodiments, the metal surface is an electrode, a microchip, a bead, a microparticle, or a nanoparticle.

[0026] In some embodiments, the metal is platinum or gold, or an oxide thereof. In some embodiments, the metal is palladium, iridium, or rhodium, or an oxide thereof.

[0027] In one aspect, provided herein, is a method of functionalizing a metallic surface comprising (a) depositing a phosphonic acid or phosphonate ester reagent on a metallic surface; and (b) heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metal surface; wherein the metallic surface comprises platinum, gold, palladium, iridium, or rhodium, an oxide thereof, or any combination thereof.

[0028] In some embodiments, depositing the phosphonic acid or phosphonate ester reagent comprises contacting the metallic surface with a solution comprising the phosphonic acid reagent and a solvent. In some embodiments, the solvent comprises an organic solvent, an aqueous solvent, or any combination or mixture thereof. In some embodiments, the organic solvent comprises acetic acid, acetone, acetonitrile, benzene, tert-butyl alcohol, tert-butyl methyl ether, carbon tetrachloride, chloroform, cyclohexane, 1,2-dichloroethane, di chi orom ethane, diethyl ether, diglyme, 1,2,- dimethoxyethane, dimethyl acetamide, dimethylformamide, dimethyl sulfoxide, dioxane, ethanol, ethyl acetate, ethyl methyl ketone, ethylene glycol, hexanes, hexamethylphosphoramide, methanol, nitromethane, pentanes, 2-proponal, pyridine, tetrahydrofuran, toluene, xylenes, or any combination thereof. In some embodiments, the organic solvent comprises ethanol, tetrahydrofuran, or toluene.

[0029] In some embodiments, the phosphonic acid or phosphonate ester reagent is present in the solution at a concentration of up to about 1 μM, 10 μM, 100 μM, 1 mM, 10 mM, 100 mM, or 1 M. In some embodiments, depositing the phosphonic acid or phosphonate ester reagent further comprises evaporating the solvent from the metallic surface. In some embodiments, evaporating the solvent from the metallic surface comprises heating the metallic surface. In some embodiments, the metallic surface is heated at a temperature of at least 30°C, at least 40°C, at least 50°C, at least 60°C, at least 70°C, at least 80°C, or at least 90°C. In some embodiments, heating the metallic surface to bind the phosphonic acid reagent with the metallic surface occurs in an oven, a vacuum oven, or a microwave reactor. In some embodiments, heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metallic surface comprises heating the metallic surface to a temperature of at least 30°C, at least 50°C, at least 70°C, at least 80°C, at least 100°C, at least 120°C, at least 140°C, at least 160°C, or at least 180°C. [0030] In some embodiments, the metallic surface is an oxidized metallic surface. In some embodiments, the oxidized metallic surface is oxidized by air oxidation, plasma treatment, ultraviolet-ozone oxidation, or chemical oxidation. In some embodiments, the method further comprises the step of oxidizing the metallic surface. In some embodiments, oxidizing the metallic surface comprises plasma treatment, ultraviolet-ozone oxidation, or chemical oxidation.

[0031] In some embodiments, the phosphonic acid or phosphonate ester reagent has the structure: wherein

R is optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, or optionally substituted heteroaryl; and each R ^E is independently H or optionally substituted alkyl.

[0032] In some embodiments, the metallic surface comprises platinum or gold, or an oxide thereof. In some embodiments, the metallic surface comprises palladium, iridium, or rhodium, or an oxide thereof.

[0033] In one aspect, provided herein, is a metallic surface microarray comprising a probe moiety bound to the metallic surface through a phosphonate residue, wherein the metallic surface comprises platinum, gold, palladium, iridium, or rhodium, or an oxide thereof, or any combination thereof. In some embodiments, the bound phosphonate residue has the structure: wherein R comprises the probe moiety and each indicates a point of attachment to the surface.

[0034] In some embodiments, the probe moiety comprises a nucleic acid, a peptide, a protein, an antibody, a small molecule, a glycan, or any combination thereof. In some embodiments, the probe moiety comprises a nucleic acid. In some embodiments, the nucleic acid comprises DNA or RNA. In some embodiments, the microarray is configured for DNA or RNA sequencing. In some embodiments, the probe moiety binds a biological agent. In some embodiments, the biological agent is a nucleic acid, a protein, a cell, or an organelle. In some embodiments, the probe moiety is specific for a biological agent. In some embodiments, the microarray comprises at least 10, at least 100, at least 1000, at least 10000, or at least 100000 unique probe features. In some embodiments, the metallic surface microarray comprises platinum or gold, or an oxide thereof. In some embodiments, the metallic surface microarray comprises palladium, iridium, or rhodium, an oxide thereof, or any combination thereof.

[0035] In one aspect, provided herein, is a drug delivery device comprising a drug moiety linked to a surface of the device through a phosphonate residue, wherein the surface comprises platinum, gold, palladium, iridium, or rhodium, an oxide thereof, or a combination thereof. In some embodiments, the phosphonate residue has the structure: wherein R comprises the drug moiety and each indicates a point of attachment to the surface.

[0036] In some embodiments, the drug moiety is linked to the phosphonate residue through a linker. In some embodiments, the linker is a cleavable linker. In some embodiments, the linker is configured to release the drug moiety. In some embodiments, the drug delivery device further comprises a targeting moiety. In some embodiments, the targeting moiety comprises an antibody or antibody fragment, a peptide, or a nucleic acid. In some embodiments, the drug delivery device is a nanoparticle, a microparticle, or a bead. In some embodiments, the surface comprises platinum or gold, an oxide thereof, or a combination thereof. In some embodiments, the surface comprises palladium, iridium, or rhodium, an oxide thereof, or a combination thereof.

[0037] In one aspect, provided herein, is a functionalized metallic surface comprising a metallic surface bound to a molecule having the structure: wherein R comprise a hydrogel. [0038] In some embodiments, the metallic surface comprises platinum, gold, palladium, iridium, rhodium, silicon, aluminum, titanium, iron, zinc, zirconium, nickel, silver, copper, cobalt, or chromium, or an oxide thereof, or any combination thereof.

[0039] In some embodiments, the hydrogel has a conductivity from about 0.001 S/m to about 10 S/m. In some embodiments, the hydrogel has a thickness from about 0.001 microns to about 10 microns. In some embodiments, the hydrogel comprises a synthetic polymer. In some embodiments, the hydrogel comprises an acrylamide polymer. In some embodiments, the acrylamide polymer comprises an N-substituted acrylamides, an N-substituted methacrylamides, or a methacrylamide, or any combination thereof. In some embodiments, the hydrogel comprises polyacrylamide, poly(diethyl acrylamide), poly(dimethylacrylamide), poly(N-isopropylacrylamide), poly(acrylic acid), poly(methacrylic acid), poly(methyl acrylate), poly(ethyl acrylate), poly(2-hydroxyethyl acrylate), poly(propyl acrylate), poly(butyl acrylate), poly(methyl methacrylate), poly(2- hydroxyethyl methacrylate), poly(tetrahydrofurfuryl methacrylate), poly(ethylene oxide), poly(propylene oxide), poly(vinyl pyrrolidone), polyoxazoline, poly(2-ethyloxazoline), or poly(N- acryloyl morpholine). In some embodiments, the metallic surface is an electrode. In some embodiments, the metallic surface is positions on an exterior surface of an electrode.

INCORPORATION BY REFERENCE

[0040] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0042] FIG. 1A shows an example reaction of a phosphonic acid reagent with a metallic surface.

[0043] FIG. 1B shows two exemplary binding modes of phosphonate modified metallic surfaces.

[0044] FIG. 2 shows an example workflow for modifying metallic surfaces.

[0045] FIG. 3A shows X-ray photoelectron spectroscopy measurements of oxidized and untreated platinum chips. [0046] FIG. 3B shows oxidation states of oxidized and untreated platinum chips measured by X- ray photoelectron spectroscopy.

[0047] FIG. 4 shows optical profilometer measurements of a bare platinum electrode without functionalization.

[0048] FIG. 5 shows optical profilometer measurements of a platinum electrode functionalized with a phosphonic acid reagent.

[0049] FIG. 6A shows a scanning electron microscopy (SEM) image of a platinum electrode surrounded by dielectric material at a tilt angle of 45°.

[0050] FIG. 6B shows an SEM image of a functionalized platinum electrode followed by a polymerization reaction.

[0051] FIG. 7 shows an SEM image of a polymer functionalized platinum electrode at a tilt angle of 0°.

[0052] FIG. 8 shows an SEM image of a polymer functionalized platinum electrode at a tilt angle of 14°.

[0053] FIG. 9 shows an SEM image of a polymer functionalized platinum electrode at a tilt angle of 14°.

[0054] FIG. 10 shows an SEM image of a polymer functionalized platinum electrode at a tilt angle of 14°.

[0055] FIG. 11 shows an SEM image of non-functionalized platinum surface at a tilt angle of 1°.

[0056] FIG. 12 shows an SEM image of non-functionalized platinum surface at a tilt angle of 45°.

[0057] FIG. 13 shows an SEM image of non-functionalized platinum surface at a tilt angle of 4°.

[0058] FIG. 14 shows an SEM image of non-functionalized platinum surface at a tilt angle of 45°.

DETAILED DESCRIPTION

[0059] Provided herein are reagents, methods, and compositions pertaining to the functionalization or derivatization of metallic surfaces. In some embodiments, the reagents comprise phosphonic acids or phosphonic acid derivatives (e.g. phosphonate esters). In some embodiments, the metallic surfaces include platinum and gold surfaces, or oxides thereof. In some embodiments, the metallic surface is platinum surface or an oxide thereof. In some embodiments, the metallic surface is a gold surface or an oxide thereof. In some embodiments, the metallic surface is palladium, iridium, or rhodium surface, or an oxide thereof. In some embodiments, the metallic surface is a palladium surface or an oxide thereof. In some embodiments, the metallic surface is an iridium surface or an oxide thereof. In some embodiments, the metallic surface is a rhodium surface or an oxide thereof. In some embodiments, the phosphonic acid or derivative thereof comprises the desired surface modification group. In some embodiments, the phosphonic acid or derivative thereof comprises a reactive handle for adding on the desired surface modification group after modification with the phosphonic acid or derivative thereof. In some embodiments, the phosphonic acid or derivative thereof comprises a capture moiety for attaching another group, such as a biological binding moiety (e.g. a peptide or oligonucleotide). An example of a metallic surface modified according to the present invention in shown in FIG. 1A, which shows an example reactant and the corresponding product bound to the metallic surface (e.g. a platinum surface). In some embodiments, the phosphonic acid reagent forms a metal phosphonate bond with the metallic surface and has one of the binding modes shown in FIG. 1B. As detailed in FIG. 1B, the P=0 bond of the phosphonate group can be coordinated to the metallic surface in a variety of modes, such an interaction between the P=0 oxygen and a metal atom on the metallic surface or an interaction between the P=0 oxygen and an adjacent -OH group on the metallic surface (for example, when the metallic surface is oxidized).

[0060] Also provided herein are uses for the modified metallic surfaces provided herein. In some preferred embodiments, the modified metallic surfaces are useful as anti-fouling surfaces for electrodes in electrophoresis-based assays. In some embodiments, these anti-fouling surfaces employ hydrogel layers. In some embodiments, the modified metallic surfaces are useful for implantation into living bodies. In some embodiments, the modified metallic surfaces have anti-corrosive properties compared to unmodified metallic surfaces. In some embodiments, the modified metallic surfaces are useful for the creation of active surfaces capable of binding analytes (e.g. in biological capture assays).

[0061] Also provided herein are methods of making the modified metallic surfaces described herein.

I. MODIFIED METALLIC SURFACES

[0062] In one aspect, provided herein, is a functionalized metallic surface. In some embodiments, the metallic surface is oxidized. In some embodiments, the metallic surface comprises platinum or gold, or an oxide thereof, or a combination thereof. In some embodiments, the metallic surface comprises platinum, or an oxide thereof. In some embodiments, the metallic surface comprises gold, or an oxide thereof. In some embodiments, the metallic surface comprises palladium, iridium, or rhodium, or an oxide thereof. In some embodiments, the metallic surface comprises palladium, or an oxide thereof. In some embodiments, the metallic surface comprises iridium, or an oxide thereof. In some embodiments, the metallic surface comprises rhodium, or an oxide thereof. In some embodiments, the metallic surface is a platinum or gold surface, or an oxide thereof. In some embodiments, the metallic surface is a platinum surface, or an oxide thereof. In some embodiments, the metallic surface is a gold surface, or an oxide thereof. In some embodiments, the metallic surface is a palladium, iridium, or rhodium, or an oxide thereof. In some embodiments, the metallic surface is a palladium surface, or an oxide thereof. In some embodiments, the metallic surface is an iridium surface, or an oxide thereof. In some embodiments, the metallic surface is a rhodium surface, or an oxide thereof. In some embodiments, the modified metallic surface is bound to a phosphonate moiety. In some embodiments, the phosphonate moiety is directly bound to the metallic surface. In some embodiments, the phosphonate moiety forms a bond with the metallic surface. In some embodiments, the phosphonate moiety forms a covalent bond with the metallic surface.

[0063] In some embodiments, the metallic surface is bound to a phosphonate moiety. In some embodiments, the phosphonate moiety is a metal phosphonate. In some embodiments, the surface bound phosphonate moiety is prepared from a phosphonic acid reagent or a phosphonic acid derivative. In some embodiments, the phosphonic acid derivative is a phosphonate ester. In some embodiments, the phosphonate ester is a C ₁ -C ₆ alkyl phosphonate ester. In some embodiments, the phosphonate ester is a methyl or ethyl phosphonate ester. In some embodiments, the phosphonic acid or phosphonate ester reagent is a bisphosphonic acid or bisphosphonate (e.g. a 1,1 bisphosphonic acid).

[0064] In some embodiments, provided herein, is a functionalized metallic surface comprising a metallic surface bound to a molecule having the structure:

In some embodiments, the functionalized metallic surface comprises a metallic surface bound to a molecule as shown in FIG. 1B. In some embodiments, each indicates a point of attachment to the metallic surface. In some embodiments, one or more is a point of attachment to the metallic surface. In some embodiments, each is a point of attachment to the metallic surface. In some embodiments, described herein, is an R moiety bound to a metallic surface through a phosphonate residue. In some embodiments is an R moiety covalently bound to a metallic surface through a phosphonate residue. In some embodiments, the metallic surface comprises platinum or an oxide thereof. In some embodiments, the metallic surface comprises gold or an oxide thereof. In some embodiments, the metallic surface comprises palladium or an oxide thereof. In some embodiments, the metallic surface comprises iridium or an oxide thereof. In some embodiments, the metallic surface comprises rhodium or an oxide thereof. In some embodiments, the metallic surface is oxidized.

[0065] R of the formula shown above can be any group. In some embodiments, R is optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, or optionally substituted heteroaryl. In some embodiments, R is optionally substituted alkyl or optionally substituted heteroalkyl.

[0066] In some embodiments, R directly comprises the desired surface modification. In some embodiments, R comprises hydrophobic residues, hydrophilic residues, charged residues, cationic residues, anionic residues, polysaccharides, hydrophobic polymers, hydrophilic polymers, antimicrobial agents, biological materials, biocompatibility materials, anti-fouling materials, conductivity materials, semi-conductive materials, heat resistant materials, anti-corrosive material, catalysts, or magnetic materials, or any combination thereof. In some embodiments, R comprises an oligonucleotide or a polypeptide. In some embodiments, R comprises a hydrogel.

Linking Moieties

[0067] In some embodiments, the surface modification group is tethered to the phosphonate group through a linking moiety. The linking moiety can be any suitable group capable of providing an attachment of the surface modification group to the phosphonate moiety.

[0068] In some embodiments, the linking moiety has the structure -L-, wherein L comprises an optionally substituted alkylene chain or an optionally substituted heteroalkylene chain. In some embodiments, the linking moiety comprises an optionally substituted alkylene chain. In some embodiments, the linking moiety comprises an unsubstituted alkylene chain. In some embodiments, the linking moiety comprises an optionally substituted heteroalkylene chain. In some embodiments, the linking moiety comprises an unsubstituted heteroalkylene chain. In some embodiments, the linking moiety comprises a chain of one to one hundred atoms. In some embodiments, the linking moiety comprises a chain of one to fifty atoms. In some embodiments, the linking moiety comprises a chain of one to forty atoms. In some embodiments, the linking moiety comprises a chain of one to twenty atoms. In some embodiments, the linking moiety comprises a chain of five to one hundred atoms. In some embodiments, the linking moiety comprises a chain of five to fifty atoms. In some embodiments, the linking moiety comprises a chain of five to forty atoms. In some embodiments, the linking moiety comprises a chain of five to twenty atoms. In some embodiments, the linking moiety comprises a chain of ten to one hundred atoms. In some embodiments, the linking moiety comprises a chain of ten to fifty atoms. In some embodiments, the linking moiety comprises a chain of ten to forty atoms. In some embodiments, the linking moiety comprises a chain of ten to twenty atoms.

[0069] In some embodiments, each atom in the chain is independently selected from C, N, O, S, Si, and P. In some embodiments, each atom in the chain is independently selected from C, N, O, and S. In some embodiments, each atom in the chain is independently selected from C, N, and O. In some embodiments, the first atom in the chain is C.

[0070] In some embodiments, L has the structure of formula:

-[Z-(CR ¹ R ² ) _n ] _m - wherein each R ¹ and R ² is independently H or optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl, or R ¹ and R ² on the same atom are taken together to form an oxo, or R ¹ s on adjacent atoms are taken together to form a double bond, or R ¹ s and R ² s on adjacent atoms are taken together to from a triple bond; each Z is independently absent, -O-, -NR ³ -, -S-, -SS-, -S(O)-, -S(O) ₂ -, -C(O)-, -C(O)O-, - C(O)NR ³ , -OC(O)O-, -NR ³ C(O)NR ³ -, -OC(O)NR ³ -, -S(O) ₂ O-, -S(O) ₂ NR ³ -, -OS(O) ₂ O-, - NR ³ S0 ₂ NR ³ -, or -OSO ₂ NR ³ -; each R ³ is independently H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl; each n is independently an integer from 1 to 30; and m is an integer from 1 to 30.

[0071] In some embodiments, each R ¹ and R ² is independently H, optionally substituted alkyl, optionally substituted heteroalkyl, or R ¹ and R ² on the same atom are taken together to form an oxo, or R ³ S on adjacent atoms are taken together to form a double bond, or R's and R ² s on adjacent atoms are taken together to from a triple bond. In some embodiments, each R ¹ and R ² is independently H, optionally substituted alkyl, R ¹ and R ² on the same atom are taken together to form an oxo, or R ¹ s on adjacent atoms are taken together to form a double bond. In some embodiments, each R ¹ and R ² is independently H, optionally substituted alkyl, R ¹ and R ² on the same atom are taken together to form an oxo, or R ¹ s on adjacent atoms are taken together to form a double bond. In some embodiments, each R ¹ and R ² is independently H, optionally substituted alkyl, or R ¹ and R ² on the same atom are taken together to form an oxo. In some embodiments, each R ¹ and R ² is independently H, optionally substituted C ₁ -C ₁₀ alkyl, or R ¹ and R ² on the same atom are taken together to form an oxo. In some embodiments, each R ¹ and R ² is independently H, optionally substituted alkyl, or R ¹ and R ² on the same atom are taken together to form an oxo. In some embodiments, each R ¹ and R ² is independently H, Ci-Cio alkyl optionally substituted with hydroxy or alkoxy, or R ¹ and R ² on the same atom are taken together to form an oxo. In some embodiments, each R ¹ and R ² is independently H or R ¹ and R ² on the same atom are taken together to form an oxo. In some embodiments, each R ¹ and R ² is H.

[0072] In some embodiments, each Z is independently absent, -O-, -NR ³ -, -S-, -C(O)-, -C(O)O-, -C(O)NR ³ , -OC(O)O-, -NR ³ C(O)NR ³ -, or -OC(O)NR ³ -. In some embodiments, each Z is independently. In some embodiments, each Z is independently absent, -O-, -NR ³ -, -C(O)O-, or - C(O)NR ³ . In some embodiments, each Z is independently absent, -O-, -C(O)O-, or -C(O)NR ³ . In some embodiments, each Z is independently -O-, -C(O)O-, or -C(O)NR ³ . In some embodiments, each Z is -O-. In some embodiments, each Z is -C(O)O-, or -C(O)NR ³ . In some embodiments, each Z is - C(O)NR ³ .

[0073] In some embodiments, each R ³ is independently H, optionally substituted alkyl, or optionally substituted cycloalkyl. In some embodiments, each R ³ is independently H or optionally substituted alkyl. In some embodiments each R ³ is independently H or C ₁ -C ₆ alkyl optionally substituted with hydroxy or alkoxy. In some embodiments, each R ³ is independently H or methyl.

[0074] In some embodiments, each n is independently an integer from 1 to 20 In some embodiments, each n is independently an integer from 1 to 15 In some embodiments, each n is independently an integer from 1 to 10 In some embodiments, each n is independently an integer from 2 to 30 In some embodiments, each n is independently an integer from 2 to 20 In some embodiments, each n is independently an integer from 2 to 15 In some embodiments, each n is independently an integer from 2 to 10.

[0075] In some embodiments, m is an integer from 1 to 25 In some embodiments, m is an integer from 1 to 20 In some embodiments, m is an integer from 1 to 15 In some embodiments, m is an integer from 1 to 10 In some embodiments, m is an integer from 1 to 5 In some embodiments, m is an integer from 2 to 30 In some embodiments, m is an integer from 2 to 25 In some embodiments, m is an integer from 2 to 20 In some embodiments, m is an integer from 2 to 15 In some embodiments, m is an integer from 2 to 10 In some embodiments, m is an integer from 2 to 5

[0076] L may comprise one or more subunit building blocks. In some embodiments, L comprises one or more subunits selected from and wherein each n is independently an integer from 1-30. In some embodiments, L comprises one or more subunits selected from and In some embodiments, L comprises one or more subunits selected from and In some embodiments, L comprises one or more subunits selected from and

[0077] In some embodiments, L comprises the structure or wherein each n is independently an integer from 1-30; and each p is independently an integer from 1-30. In some embodiments, L has the structure or wherein each n is independently an integer from 1-30; and each p is independently an integer from 1-30. In some embodiments, L has the structure or O

. In some embodiments, L has the structure

[0078] In some embodiments, p is an integer from 1 to 20 In some embodiments, p is an integer from 1 to 15 In some embodiments, p is an integer from 1 to 10 In some embodiments, p is an integer from 1 to 5 In some embodiments, p is an integer from 2 to 30 In some embodiments, p is an integer from 2 to 20 In some embodiments, p is an integer from 2 to 15 In some embodiments, p is an integer from 2 to 10 In some embodiments, p is an integer from 2 to 5

[0079] In some embodiments, L comprises a polymer. Any polymer may be used for the linking moiety L. The polymer may be branched or linear. In some embodiments, the polymer comprises a polyethylene, a polypropylene, a polyvinyl halide, a polystyrene, a nylon, a polyamide, a polyester, a polyaramide, a polyacrylate, a poly methacrylate, a poly tetrafluoroethylene, a polysaccharide, a poly(alkylene oxide), a poly(vinyl pyrrolidone), a poly(vinyl alcohol), a polyoxazoline, a poly(N- acryloyl morpholine), or any combination or derivative thereof. In some embodiments, the polymer comprises a polyethylene, a nylon, a polyamide, a polyester, a polyacrylate, a poly methacrylate, a poly(alkylene oxide), a poly(vinyl pyrrolidone), a poly(vinyl alcohol), or any combination or derivative thereof. In some embodiments, the polymer comprises a polyamide, a polyester, a polyacrylate, a poly methacrylate, a poly(alkylene oxide), or any combination or derivative thereof. In some embodiments, the polymer comprises a poly(alkylene oxide). In some embodiments, the polymer comprises polyethylene glycol. In some embodiments, the polymer comprises a poly methacrylate. In some embodiments, the poly methacrylate is a hydroxyalkyl methacrylate. In some embodiments, the poly methacrylate is a C ₁ -C20 hydroxyalkyl methacrylate. In some embodiments, the poly methacrylate is hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxypentyl methacrylate, hydroxyhexyl methacrylate, hydroxyheptyl methacrylate, or hydroxyoctyl methacrylate.

[0080] In some embodiments, L comprises a cleavable linker. In some embodiments, the linking moiety comprises a cleavable linker. Any cleavable linker may be used with the present invention. In some embodiments, the cleavable linker is a photocleavable linker, a chemically cleavable linker, or an enzyme cleavable linker.

Reactive Handles and Capture Moieties

[0081] The linking moiety may be used to link the phosphonate moiety to a reactive handle. The reactive handle is configured to allow the additional of additional surface functionalization reagents. CLICK chemistry reagents are one example of compatible reactive handles. Any suitable reactive group may be used. In some embodiments, the reactive handle is represented by X. In some embodiments, R has the structure X-L-, wherein L is any of the linking moieties provided herein.

[0082] In some embodiments, X comprises a reactive functional group. Any suitable functional group may be employed for this purpose. In some embodiments, X comprises a reactive functional group selected from an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, acid, activated ester, alkene, alcohol, halide, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, oxime, isocyanate, isothiocyanate, hydrazine, and hydrazide, or any combination thereof. In some embodiments, X comprises a reactive functional group selected from an azide, alkyne, sulfhydryl, maleimide, activated ester, halide, acyl halide, epoxide, aldehyde, and ketone, or any combination thereof. In some embodiments, X comprises a reactive functional group selected from an azide, alkyne, sulfhydryl, maleimide, halide, and epoxide, or any combination thereof. In some embodiments, X comprises an azide. In some embodiments, X comprises an alkyne. In some embodiments, X comprises a cyclooctyne. In some embodiments, X comprises a dibenzolcyclooctyne. In some embodiments, X comprises a maleimide. In some embodiments, X comprises a halide. In some embodiments, X comprises an epoxide. In some embodiments, X comprises a sulfhydryl. In some embodiments, X comprises a carboxylic acid. In some embodiments,

X comprises an amine. In some embodiments, X comprises an alkene. In some embodiments, X comprises a CLICK chemistry reagent.

[0083] In some embodiments, X has the structure X ¹ -L ^x -ZX ^x - , wherein

Z ^x is a bond, -O-, -NR ⁴ -, -S-, -SS-, -S(O)-, S(O) ₂ -, -C(O)-, -C(O)O-, -C(O)NR ⁴ , -OC(O)O-, - NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, -S(O) ₂ O-, -S(O) ₂ NR ⁴ ., -OS(O) ₂ O-, -NR ⁴ S(O) ₂ NR ⁴ -, or - 0S(O) ₂ NR ⁴ -;

L ^x is absent, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted heteroarylalkyl, optionally substituted arylheteroalkyl, or optionally substituted heteroarylheteroalkyl;

X ¹ comprises an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, carboxylic acid, activated ester, alkene, alcohol, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, oxime, isocyanate, isothiocyanate, hydrazine, or hydrazide; and each R ⁴ is independently H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl. [0084] In some embodiments, Z ^x serves as a point of attachment of linking the reactive handle to the linking moiety L. Any group allowing the attachment of the reactive moiety to the linking moiety may be employed. In some embodiments, Z ^x is a bond, -O-, -NR ⁴ -, -S-, -SS-, -C(O)-, -C(O)O- , -C(O)NR ⁴ , -OC(O)O-, -NR ⁴ C(O)NR ⁴ -, or -OC(O)NR ⁴ -. In some embodiments, Z ^x is a bond, -O-, - NR ⁴ -, -C(O)-, -C(O)O-, or -C(O)NR ⁴ -. In some embodiments, Z ^x is a bond. In some embodiments, Z ^x is -O-. In some embodiments, Z ^x is -NR ⁴ -. In some embodiments, Z ^x is -C(O)-. In some embodiments, Z ^x is -C(O)O-. In some embodiments, Z ^x is -C(O)NR ⁴ -.

[0085] L ^x' serves as a secondary linking moiety between the point of attachment to the linking moiety L and the reactive functional group of X. Any suitable linker may be employed. In some embodiments, L ^x is absent, optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted heteroalkylene, optionally substituted arylene, optionally substituted arylalkylene, optionally substituted heteroarylalkylene, optionally substituted arylheteroalkylene, or optionally substituted heteroarylheteroalkylene. In some embodiments, L ^x is optionally substituted alkylene or optionally substituted heteroalkylene. In some embodiments, L ^x is optionally substituted alkylene. In some embodiments, L ^x is alkylene. In some embodiments, L ^x is optionally substituted heteroalkylene. In some embodiments, L ^x is heteroalkylene. In some embodiments, L ^x comprises a cleavable linker group.

[0086] In some embodiments, L ^x has the structure:

-(CR ⁵ R ⁶ ) _r - wherein each R ⁵ and R ⁶ is independently H, halogen, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl, or R ⁵ and R ⁶ on the same atom are taken together to form an oxo, or R ⁵ s on adjacent atoms are taken together to form a double bond, or R ⁵ S and R ⁶ s on adjacent atoms are taken together to from a triple bond; and r is an integer from 0-30.

[0087] In some embodiments, each R ⁵ and R ⁶ is independently H, optionally substituted alkyl, or optionally substituted heteroalkyl; or R ⁵ and R ⁶ on the same atom are taken together to form an oxo; or R ⁵ S on adjacent atoms are taken together to form a double bond. In some embodiments, each R ⁵ and R ⁶ is independently H, optionally substituted alkyl, or optionally substituted heteroalkyl. In some embodiments, each R ⁵ and R ⁶ is independently H, optionally substituted alkyl. In some embodiments, each R ⁵ and R ⁶ is independently H or optionally substituted C ₁ -C ₆ alkyl. In some embodiments, each R ⁵ and R ⁶ is independently H or C ₁ -C ₆ alkyl. In some embodiments, each R ⁵ and R ⁶ is independently H or C ₁ -C ₃ alkyl. [0088] In some embodiments, r is an integer from 0 to 30. In some embodiments, r is an integer from 0 to 20. In some embodiments, r is an integer from 0 to 10. In some embodiments, r is an integer from 0 to 5. In some embodiments, r is 0 or 1.

[0089] In some embodiments, X ¹ comprises an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, carboxylic acid, activated ester, alkene, alcohol, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, oxime, isocyanate, isothiocyanate, hydrazine, or hydrazide. In some embodiments, X ¹ is azide, alkyne, halide, sulfhydryl, maleimide, amine, carboxylic acid, alkene, alcohol, epoxide, aldehyde, ketone, imine, or hydrazine. In some embodiments, X ¹ is an amine, carboxylic acid, azide, alkyne, halide, alkene, or sulfhydryl.

[0090] In some embodiments, X has the structure some embodiments, X has the structure . In some embodiments, X has the structure . In some embodiments, X has the structure

[0091] In some embodiments, X is is some

[0092] X may also comprise a capture moiety. The capture moiety may be any type of molecule capable of selectively capturing a desired material. In some embodiments, the capture moiety comprises biotin, avidin, streptavidin, a nucleic acid, a peptide, a protein, or any combination thereof. In some embodiments, the capture moiety comprises biotin. In some embodiments, the capture moiety comprises avidin. In some embodiments, the capture moiety comprises streptavidin. In some embodiments, the capture moiety comprises a nucleic acid. In some embodiments, the nucleic acid is an aptamer. In some embodiments, the nucleic acid is a capture probe. In some embodiments, the capture moiety is a peptide. In some embodiments, the capture moiety is a protein.

[0093] Any of the modified metallic surfaces provided herein may be manufactured or distributed as a kit. In some embodiments, the kit comprises the modified metallic surface and instructions for use. In some embodiments, the modified metallic surface comprises a reactive handle or capture moiety linked to the metallic surface. In some embodiments, the instructions for use provide a protocol for linking of additional moieties to the metallic surface via the reactive handle or capture moiety.

Surface Modifications

[0094] In some embodiments, the surface modification is attached to the phosphonate moiety by a linking moiety. In some embodiments, the surface modification is directly connected to the phosphonate moiety. In some embodiments, the surface modification group is attached to the phosphonate moiety through a reaction product of any of the reactive handles or capture moieties X described above.

[0095] Any desired surface modification group can be applied to the metallic surface by the metal phosphonate bonds described herein. In some embodiments, the surface modification group selected from hydrophobic residues, hydrophilic residues, charged residues, cationic residues, anionic residues, polysaccharides, hydrophobic polymers, hydrophilic polymers, antimicrobial agents, biological materials, biocompatibility materials, anti-fouling materials, conductivity materials, semi- conductive materials, heat resistant materials, anti-corrosive material, catalysts, and magnetic materials, or any combination thereof. In some embodiments, the surface modification group is a hydrogel. [0096] In some embodiments, the surface modification is represented by Y. In some embodiments, R has the structure Y-L-, wherein L is any of the linking moieties provided herein.

[0097] In some embodiments, Y has the structure Y ¹ -L ^Y -Z ^y -. In some embodiments, Y ¹ represents the surface modification group. In some embodiments, L ^Y serves as a secondary linking moiety between the point of attachment to the linking moiety L and the surface modification group of Y. In some embodiments, Z ^Y serves as a point of attachment of linking the surface modification group to the linking moiety L.

[0098] In some embodiments, Z ^Y is a bond, -O-, -NR ⁴ -, -S-, -SS-, -S(O)-, S(O) ₂ -, -C(O)-, - C(O)O-, -C(O)NR ⁴ , -OC(O)O-, -NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, -S(O) ₂ O-, -S(O) ₂ NR ⁴ ., -OS(O) ₂ O-, - NR ⁴ S(O) ₂ NR ⁴ -, -OS(O) ₂ NR ⁴ -, or reaction product formed by a covalent bond forming reaction between an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, carboxylic acid, activated ester, alkene, alcohol, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, oxime, isocyanate, isothiocyanate, hydrazine, or hydrazide and a suitable complementary reactive group. In some embodiments, Z ^Y is a reaction product formed by a covalent bond forming reaction between an azide, alkyne, tetrazine, halide, sulfhydryl, disulfide, maleimide, amine, carboxylic acid, activated ester, alkene, alcohol, acyl halide, sulfonic acid, sulfmic acid, sulfonyl halide, epoxide, aldehyde, ketone, imine, hydrazine, or hydrazide and a suitable complementary reactive group. In some embodiments, Z ^Y is a reaction product formed by a covalent bond forming reaction between an azide, alkyne, halide, sulfhydryl, maleimide, alkene, or epoxide and a suitable complementary reactive group. In some embodiments, Z ^Y is a bond, -O-, -NR ⁴ -, -S-, - SS-, -S(O)-, S(O) ₂ -, -C(O)-, -C(O)O-, -C(O)NR ⁴ , -OC(O)O-, -NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, - S(O) ₂ O-, -S(O) ₂ NR ⁴ ., -OS(O) ₂ O-, -NR ⁴ S(O) ₂ NR ⁴ -, -OS(O) ₂ NR ⁴ -. In some embodiments, Z ^Y is a bond, -O-, -NR ⁴ -, -S-, -SS-, -C(O)-, -C(O)O-, or -C(O)NR ⁴ . In some embodiments, Z ^Y is -SS-, -C(O)- , -C(O)O-, or -C(O)NR ⁴ . In some embodiments, Z ^Y is a bond, -O-, -NR ⁴ -, -S-, -SS-, -S(O)-, S(O) ₂ -, -C(O)-, -C(O)O-, -C(O)NR ⁴ -, -OC(O)O-, -NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, -S(O) ₂ O-, -S(O) ₂ NR ⁴ -, -

0S(O) ₂ O-, -NR ⁴ S(O) ₂ NR ⁴ -, -OS(O) ₂ NR ⁴ -,

In some embodiments, Z ^Y is a bond, -O-, -NR ⁴ -, -S-, -SS-, -S(O)-, S(O) ₂ -, -C(O)-, - C(O)O-, -C(O)NR ⁴ -, -OC(O)O-, -NR ⁴ C(O)NR ⁴ -, -OC(O)NR ⁴ -, -S(O) ₂ O-, -S(O) ₂ NR ⁴ -, -OS(O) ₂ O-, - NR ⁴ S(O) ₂ NR ⁴ -, -OS(O) ₂ NR ⁴ -.

[0099] In some embodiments, L ^Y is absent, optionally substituted alkylene, optionally substituted cycloalkylene, optionally substituted alkenylene, optionally substituted alkynylene, optionally substituted heteroalkylene, optionally substituted arylene, optionally substituted arylalkylene, optionally substituted heteroarylalkylene, optionally substituted arylheteroalkylene, or optionally substituted heteroarylheteroalkylene. In some embodiments, L ^Y is absent, optionally substituted alkylene, or optionally substituted heteroalkylene. In some embodiments, L ^Y is alkylene. In some embodiments, L ^Y is heteroalkylene. In some embodiments, L ^Y is absent. In some embodiments, L ^Y comprises a cleavable linker group.

[0100] In some embodiments each R ⁴ is independently H, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted heteroalkyl, optionally substituted aryl, or optionally substituted heteroaryl. In some embodiments, each R ⁴ is independently H, optionally substituted alkyl, or optionally substituted heteroalkyl. In some embodiments, each R ⁴ is independently H or C ₁ -C ₆ alkyl. In some embodiments, each R ⁴ is independently H or methyl. [0101] In some embodiments, Y ¹ comprises at least one surface modification residue. Any suitable surface modification residue may be employed.

[0102] In some embodiments, Y ¹ comprises hydrophobic residues. In some embodiments, the hydrophobic residue is a fatty acid or a fatty acid derivative. In some embodiments, the hydrophobic residue is a fluorinated fatty acid.

[0103] In some embodiments, the hydrophobic residues comprise a hydrophobic polymer. In some embodiments, the hydrophobic polymer comprises a polyethylene, a polypropylene, a polystyrene, a polyvinylhalide, a polytetrafluoroethylene, a polymethylmethacrylate, a polycarbonate, a polyether-urethane, a polydimethylsiloxane, or any combination or derivative thereof. In some embodiments, the hydrophobic polymer comprises a polyethylene. In some embodiments, the hydrophobic polymer comprises a polypropylene. In some embodiments, the hydrophobic polymer comprises a polystyrene. In some embodiments, the hydrophobic polymer comprises a polyvinylhalide. In some embodiments, the hydrophobic polymer comprises a polytetrafluoroethylene. In some embodiments, the hydrophobic polymer comprises a polymethylmethacrylate. In some embodiments, the hydrophobic polymer comprises a polycarbonate. In some embodiments, the hydrophobic polymer comprises a polyether-urethane. In some embodiments, the hydrophobic polymer comprises a polydimethylsiloxane. In some embodiments, the hydrophobic polymer comprises a polysilane. In some embodiments, the hydrophobic polymer comprises a fluoropolymer.

[0104] In some embodiments, Y ¹ comprises hydrophilic residues. Any suitable hydrophilic residues may be used. In some embodiments, the hydrophilic residues comprise a monosaccharide or a polysaccharide. In some embodiments, the hydrophilic residues comprise a hydrophilic polymer. In some embodiments, the hydrophilic polymer comprises a polyacrylamide, a polyacrylate, a poly methacrylate, a poly(alkylene oxide), a poly(vinyl pyrrolidone), a poly(vinyl alcohol), a polyoxazoline, a poly(N-acryloyl morpholine), or any combination of derivative thereof. In some embodiments, the hydrophilic polymer comprises a polyacrylamide. In some embodiments, the hydrophilic polymer comprises a polyacrylate. In some embodiments, the hydrophilic polymer comprises a poly methacrylate. In some embodiments, the hydrophilic polymer comprises a poly(alkylene oxide). In some embodiments, the hydrophilic polymer comprises a poly(vinyl pyrrolidone). In some embodiments, the hydrophilic polymer comprises a poly(vinyl alcohol). In some embodiments, the hydrophilic polymer comprises a polyoxazoline. In some embodiments, the hydrophilic polymer comprises a poly(N-acryloyl morpholine).

[0105] In some embodiments, the hydrophilic polymer comprises polyacrylamide, poly(diethyl acrylamide), poly(dimethylacrylamide), poly(N-isopropylacrylamide), poly(acrylic acid), poly(methacrylic acid), poly(methyl acrylate), poly(ethyl acrylate), poly(2-hydroxyethyl acrylate), poly(propyl acrylate), poly(butyl acrylate), poly(methyl methacrylate), poly(2-hydroxyethyl methacrylate), poly(tetrahydrofurfuryl methacrylate), poly(ethylene oxide), poly(propylene oxide), poly(vinyl pyrrolidone), polyoxazoline, poly(2-ethyloxazoline), or poly(N-acryloyl morpholine). In some embodiments, the hydrophilic polymer comprises polyacrylamide. In some embodiments, the hydrophilic polymer comprises poly(N,N-diethyl acrylamide). In some embodiments, the hydrophilic polymer comprises poly(dimethylacrylamide). In some embodiments, the hydrophilic polymer comprises poly(N-isopropylacrylamide). In some embodiments, the hydrophilic polymer comprises poly(acrylic acid). In some embodiments, the hydrophilic polymer comprises poly(methacrylic acid). In some embodiments, the hydrophilic polymer comprises poly(methyl acrylate). In some embodiments, the hydrophilic polymer comprises poly(ethyl acrylate). In some embodiments, the hydrophilic polymer comprises poly(2-hydroxyethyl acrylate). In some embodiments, the hydrophilic polymer comprises poly(propyl acrylate). In some embodiments, the hydrophilic polymer comprises poly(butyl acrylate). In some embodiments, the hydrophilic polymer comprises poly(methyl methacrylate). In some embodiments, the hydrophilic polymer comprises a poly methacrylate. In some embodiments, the poly methacrylate is a hydroxyalkyl methacrylate. In some embodiments, the poly methacrylate is a C ₁ -C ₂₀ hydroxyalkyl methacrylate. In some embodiments, the poly methacrylate is hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxypentyl methacrylate, hydroxyhexyl methacrylate, hydroxyheptyl methacrylate, or hydroxyoctyl methacrylate. In some embodiments, the hydrophilic polymer comprises poly(2-hydroxyethyl methacrylate). In some embodiments, the hydrophilic polymer comprises poly(tetrahydrofurfuryl methacrylate). In some embodiments, the hydrophilic polymer comprises poly(ethylene oxide). In some embodiments, the hydrophilic polymer comprises poly(propylene oxide). In some embodiments, the hydrophilic polymer comprises poly(vinyl pyrrolidone). In some embodiments, the hydrophilic polymer comprises polyoxazoline. In some embodiments, the hydrophilic polymer comprises poly(2-ethyloxazoline). In some embodiments, the hydrophilic polymer comprises poly(N-acryloyl morpholine).

[0106] In some embodiments, the surface modification group of Y comprises the structure wherein each R ⁷ is independently optionally substituted C ₁ -C ₃ alkyl or optionally substituted C ₁ -C ₃ hydroxyalkyl; each R ⁸ is independently H or C ₁ -C ₃ alkyl; each X ⁷ is independently absent, -O-, -S-, or NR ⁹ ; each R ⁹ is independently H or optionally substituted C ₁ -C ₆ alkyl; and s is an integer from 1 to 1000000.

[0107] In some embodiments, the structure linked to the linking moiety.

[0108] In some embodiments, each R ⁷ is independently H, C ₁ -C ₃ alkyl or C ₁ -C ₃ hydroxyalkyl. In some embodiments, each R ⁷ is independently H, methyl, ethyl, propyl, isopropyl, 2-hydroxyethyl, 3- hydroxypropyl, or 2-hydroxypropyl.

[0109] In some embodiments, each R ⁸ is independently H, ethyl, methyl, or propyl. In some embodiments, each R ⁸ is independently H or methyl. In some embodiments, each R ⁸ is H. In some embodiments, each R ⁸ is methyl.

[0110] In some embodiments, each X ⁷ is independently absent, -O-, -S-, or NR ⁹ . In some embodiments, each X ⁷ is independently -O- or -NR ⁹ . In some embodiments, each X ⁷ is -O-. In some embodiments, each X ⁷ is independently -NR ⁹ . In some embodiments, each X ⁷ is absent.

[0111] In some embodiments, each R ⁹ is independently H or C ₁ -C ₃ alkyl optionally substituted with hydroxy or alkoxy. In some embodiments, each R ⁹ is independently H or C ₁ -C ₃ alkyl. In some embodiments, each R ⁹ is independently H or methyl. In some embodiments, each R ⁹ is H.

[0112] In some embodiments, s is an integer from 1 to 1000000. In some embodiments, s is an integer from 1 to 100000. In some embodiments, s is an integer from 1 to 10000. In some embodiments, s is an integer from 1 to 1000. In some embodiments, s is an integer from 1 to 100. In some embodiments, s is an integer from 10 to 1000000. In some embodiments, s is an integer from 10 to 100000. In some embodiments, s is an integer from 10 to 10000. In some embodiments, s is an integer from 10 to 1000. In some embodiments, s is an integer from 10 to 100. In some embodiments, s is an integer from 1 to 100. In some embodiments, s is an integer from 100 to 1000000. In some embodiments, s is an integer from 100 to 100000. In some embodiments, s is an integer from 10 to 10000. In some embodiments, s is an integer from 100 to 1000. [0113] In some embodiments, the surface modification group comprises cationic residues. In some embodiments, Y ¹ comprises cationic residues. In some embodiments, the cationic residues comprise amine groups, substituted amine groups, quaternary amine groups, or any combination thereof. In some embodiments, the cationic residues are amine groups. In some embodiments, the cationic residues are substituted amine groups. In some embodiments, the cationic residues comprise protonated amine groups, protonated substituted amine groups, or quaternary amine groups, or any combination thereof.

[0114] In some embodiments, the Y ¹ comprises a cationic polymer. Any polymerizable monomer comprising a cationic group may be used. In some embodiments, the cationic polymer comprises a poly(ethyleneimine) (PEI), a poly amino acid (e.g. polylysine, polyarginine), a polypyridinium, a polyammonium, a polyacrylate comprising an amino group, a polyacrylamide comprising an amino group, or a chitosan.

[0115] In some embodiments, the surface modification group comprises anionic residues. In some embodiments, Y ¹ comprises anionic residues. Any anionic residue may be used. In some embodiments, the anionic residues comprise carboxylates, sulfonates, sulfmates, phosphates, phosphonates, or any combination thereof. In some embodiments, the anionic residues are carboxylates. In some embodiments, the anionic residues are sulfonates. In some embodiments, the anionic residues are sulfmates. In some embodiments, the anionic residues are phosphates. In some embodiments, the anionic residues are phosphonates.

[0116] In some embodiments, the surface modification group comprises an anionic polymer. In some embodiments, Y ¹ comprises an anionic polymer. In some embodiments, the anionic polymer comprises anionic groups selected from carboxylates, sulfonates, sulfmates, phosphates, and phosphonates, or any combination thereof. In some embodiments, the anionic polymer comprises a poly amino acid (e.g. poly glutamic acid, poly aspartic acid), a poly acrylate, a poly methacrylate, a polysulfonate, or a polyacid.

[0117] In some embodiments, the surface modification group is a zwitterionic group. In some embodiments, Y ¹ comprises a zwitterionic group. In some embodiments, Y comprises a zwitterionic group. Any combination of the listed cationic or anionic groups listed herein may be employed.

[0118] In some embodiments, the surface modification group comprises a hydrogel. In some embodiments, Y comprises a hydrogel. In some embodiments, Y ¹ comprises a hydrogel. In some embodiments, R comprises a hydrogel. Any hydrogel may be linked with the phosphonic acid reagents herein. The properties of the hydrogel can be modified for any desired purpose of the functionalized metallic surfaces provide herein. In some embodiments, the properties of the hydrogel are optimized for use with metal electrodes. Further description of hydrogels which may be attached to the metal surfaces can be found below in the “ Hydrogel Surface Modifications” section.

[0119] In some embodiments, the surface modification group comprises a probe moiety. In some embodiments, Y comprises a probe moiety. In some embodiments, Y ¹ comprises a probe moiety. In some embodiments, R comprises a probe moiety. Any type of probe moiety may be employed. In some embodiments, the probe moiety comprises a binding agent specific for an analyte or target. In some embodiments, the probe moiety comprises a nucleic acid, a peptide, a protein, an antibody, a small molecule, a glycan, or any combination thereof.

[0120] In some embodiments, the probe moiety comprises a nucleic acid. In some embodiments, the nucleic acid comprises DNA or RNA. In some embodiments, the nucleic acid is configured to hybridize with a target moiety or analyte. In some embodiments, the nucleic acid comprises an aptamer. In some embodiments, the nucleic acid comprises unnatural oligonucleotides.

[0121] In some embodiments, the probe moiety comprises a peptide. In some embodiments, the probe moiety comprises a protein. In some, the probe moiety comprises a protein fragment. In some embodiments, the probe moiety comprises an antibody. In some embodiments, the probe moiety comprises an antibody fragment. In some embodiments, the probe moiety comprises a small molecule. In some embodiments, the probe moiety comprises a glycan.

[0122] In some embodiments, the surface modification group comprises a drug moiety. The drug moiety may be linked to the phosphonate moiety by any linking moiety. In some embodiments, the drug moiety is linked to the surface through a cleavable linker. In some embodiments, the linker is configured to release the drug moiety.

[0123] In some embodiments, the surface modification group comprises a targeting moiety. In some embodiments, the targeting moiety is specific for a particular biomarker. The targeting moiety may be any suitable group. In some embodiments, the targeting moiety comprises an antibody or antibody fragment, a peptide, or a nucleic acid. In some embodiments, a targeting moiety and a drug moiety are attached to the same surface.

Hydrogel Surface Modifications

[0124] Also provided herein are hydrogels which may be linked to metallic surfaces through bonds between a phosphonate group and the metallic surface. In addition to being applied to platinum, gold, palladium, iridium, or rhodium surfaces described herein, these hydrogels may also be linked to other metal surfaces capable of forming bonds with phosphonates, including without limitation silicon, aluminum, titanium, iron, zinc, zirconium, nickel, silver, copper, cobalt, or chromium, or an oxide thereof, or any combination thereof. In some embodiments, the hydrogel is linked a metallic surface comprising platinum. In some embodiments, the hydrogel is linked a metallic surface comprising gold. In some embodiments, the hydrogel is linked a metallic surface comprising palladium. In some embodiments, the hydrogel is linked a metallic surface comprising iridium. In some embodiments, the hydrogel is linked a metallic surface comprising rhodium. In some embodiments, the hydrogel is linked a metallic surface comprising silicon. In some embodiments, the hydrogel is linked a metallic surface comprising aluminum. In some embodiments, the hydrogel is linked a metallic surface comprising titanium. In some embodiments, the hydrogel is linked a metallic surface comprising iron. In some embodiments, the hydrogel is linked a metallic surface comprising zinc.

[0125] The hydrogels provided herein may be linked to the metallic surface through any of the linking moieties provided herein, including the linking moieties provided in the "Linking Moieties” section, or linked through a bond formed through a reaction of any of the reactive handles provided therein.

[0126] In some embodiments, the surface modification group comprises a hydrogel. In some embodiments, Y comprises a hydrogel. In some embodiments, Y ¹ comprises a hydrogel. In some embodiments, R comprises a hydrogel. Any hydrogel may be linked with the phosphonic acid reagents herein. The properties of the hydrogel can be modified for any desired purpose of the functionalized metallic surfaces provide herein. In some embodiments, the properties of the hydrogel are optimized for use with metal electrodes.

[0127] In some embodiments, hydrogels are employed on electrodes configured for electrophoretic analysis of biological samples. When the metallic surface comprises an electrode, overlaying electrode structures with one or more layers of materials can reduce the deleterious electrochemistry effects, including but not limited to electrolysis reactions, heating, and chaotic fluid movement that may occur on or near the electrodes, and still allow the effective separation of cells, bacteria, virus, nanoparticles, DNA, and other biomolecules to be carried out. In some embodiments, the hydrogel layered over the electrode structures may comprise one or more porous layers.

[0128] In some embodiments, the hydrogel has sufficient mechanical strength and is relatively chemically inert such that it will be able to endure the electrochemical effects at the electrode surface without disconfiguration or decomposition. In some embodiments, the hydrogel is sufficiently permeable to small aqueous ions, but keeps biomolecules away from the electrode surface. In some embodiments, the hydrogel comprises a gradient of porosity, wherein the bottom of the hydrogel layer has greater porosity than the top of the hydrogel layer.

[0129] In some embodiments, Y comprises a hydrogel. In some embodiments, Y ¹ comprises a hydrogel. [0130] In some embodiments, the hydrogel has a conductivity from about 0.001 S/m to about 10 S/m. In some embodiments, the hydrogel has a conductivity from about 0.01 S/m to about 10 S/m. In some embodiments, the hydrogel has a conductivity from about 0.1 S/m to about 10 S/m. In some embodiments, the hydrogel has a conductivity from about 1.0 S/m to about 10 S/m. In some embodiments, the hydrogel has a conductivity from about 0.01 S/m to about 5 S/m. In some embodiments, the hydrogel has a conductivity from about 0.01 S/m to about 4 S/m. In some embodiments, the hydrogel has a conductivity from about 0.01 S/m to about 3 S/m. In some embodiments, the hydrogel has a conductivity from about 0.01 S/m to about 2 S/m. In some embodiments, the hydrogel has a conductivity from about 0.1 S/m to about 5 S/m. In some embodiments, the hydrogel has a conductivity from about 0.1 S/m to about 4 S/m. In some embodiments, the hydrogel has a conductivity from about 0.1 S/m to about 3 S/m. In some embodiments, the hydrogel has a conductivity from about 0.1 S/m to about 2 S/m. In some embodiments, the hydrogel has a conductivity from about 0.1 S/m to about 1.5 S/m. In some embodiments, the hydrogel has a conductivity from about 0.1 S/m to about 1.0 S/m.

[0131] In some embodiments, the hydrogel has a conductivity of about 0.1 S/m. In some embodiments, the hydrogel has a conductivity of about 0.2 S/m. In some embodiments, the hydrogel has a conductivity of about 0.3 S/m. In some embodiments, the hydrogel has a conductivity of about 0.4 S/m. In some embodiments, the hydrogel has a conductivity of about 0.5 S/m. In some embodiments, the hydrogel has a conductivity of about 0.6 S/m. In some embodiments, the hydrogel has a conductivity of about 0.7 S/m. In some embodiments, the hydrogel has a conductivity of about 0.8 S/m. In some embodiments, the hydrogel has a conductivity of about 0.9 S/m. In some embodiments, the hydrogel has a conductivity of about 1.0 S/m.

[0132] In some embodiments, the hydrogel has a thickness from about 0.001 microns to about 10 microns. In some embodiments, the hydrogel has a thickness from about 0.001 microns to about 5 microns. In some embodiments, the hydrogel has a thickness from about 0.001 microns to about 1 microns. In some embodiments, the hydrogel has a thickness from about 0.001 microns to about 0.5 microns. In some embodiments, the hydrogel has a thickness from about 0.01 microns to about 10 microns. In some embodiments, the hydrogel has a thickness from about 0.01 microns to about 5 microns. In some embodiments, the hydrogel has a thickness from about 0.01 to about 1 microns. In some embodiments, the hydrogel has a thickness from about 0.1 microns to about 10 microns. In some embodiments, the hydrogel has a thickness from about 0.1 microns to about 5 microns. In some embodiments, the hydrogel has a thickness from about 0.1 microns to about 4 microns. In some embodiments, the hydrogel has a thickness from about 0.1 microns to about 3 microns. In some embodiments, the hydrogel has a thickness from about 0.1 microns to about 2 microns. In some embodiments, the hydrogel has a thickness from about 1 micron to about 5 microns. In some embodiments, the hydrogel has a thickness from about 1 micron to about 4 microns. In some embodiments, the hydrogel has a thickness from about 1 micron to about 3 microns. In some embodiments, the hydrogel has a thickness from about 1 micron to about 2 microns. In some embodiments, the hydrogel has a thickness from about 0.5 microns to about 1 micron.

[0133] In some embodiments, the hydrogel comprises any suitable synthetic polymer forming a hydrogel. In general, any sufficiently hydrophilic and polymerizable molecule may be utilized in the production of a synthetic polymer hydrogel for use as disclosed herein. Polymerizable moieties in the monomers may include alkenyl moieties including but not limited to substituted or unsubstituted a,b, unsaturated carbonyls wherein the double bond is directly attached to a carbon which is double bonded to an oxygen and single bonded to another oxygen, nitrogen, sulfur, halogen, or carbon; vinyl, wherein the double bond is singly bonded to an oxygen, nitrogen, halogen, phosphorus or sulfur; allyl, wherein the double bond is singly bonded to a carbon which is bonded to an oxygen, nitrogen, halogen, phosphorus or sulfur; homoallyl, wherein the double bond is singly bonded to a carbon which is singly bonded to another carbon which is then singly bonded to an oxygen, nitrogen, halogen, phosphorus or sulfur; alkynyl moieties wherein a triple bond exists between two carbon atoms. In some embodiments, acryloyl or acrylamido monomers such as acrylates, methacrylates, acrylamides, methacrylamides, etc., are useful for formation of hydrogels as disclosed herein. More preferred acrylamido monomers include acrylamides, N-substituted acrylamides, N-substituted methacrylamides, and methacrylamide. In some embodiments, a hydrogel comprises polymers such as epoxide-based polymers, vinyl-based polymers, allyl-based polymers, homoallyl-based polymers, cyclic anhydride-based polymers, ester-based polymers, ether-based polymers, alkylene-glycol based polymers (e.g., polypropylene glycol), and the like.

[0134] In some embodiments, the hydrogel comprises poly(2-hydroxyethyl methacrylate) (pHEMA), cellulose acetate, cellulose acetate phthalate, cellulose acetate butyrate, or any appropriate acrylamide or vinyl-based polymer, or a derivative thereof.

[0135] In some embodiments, the hydrogel is polymerized via atom-transfer radical- polymerization via (ATRP). In some embodiments, the hydrogel is polymerized via reversible addition-fragmentation chain-transfer (RAFT) polymerization. In some embodiments, the hydrogel is polymerized onto the metallic surface through a reactive group linked to the phosphonate bound to the metallic surface, wherein the reactive group comprises halide in an alpha position to a carbonyl. In some embodiments, the alpha position to a carbonyl is a tertiary carbon. In some embodiments, the reactive group has the structure (CH ₃ ) ₂ BrC-C(O)-. [0136] In some embodiments, additives are added to a hydrogel to increase conductivity of the gel. In some embodiments, hydrogel additives are conductive polymers (e.g., PEDOT: PSS), salts (e.g., copper chloride), metals (e.g., gold), plasticizers (e.g., PEG200, PEG 400, or PEG 600), or cosolvents. In some embodiments, the hydrogel also comprises compounds or materials which help maintain the stability of the DNA hybrids, including, but not limited to histidine, histidine peptides, polyhistidine, lysine, lysine peptides, and other cationic compounds or substances.

Metallic Surfaces

[0137] Any suitable metallic surface may be modified with the compositions and systems according to the present disclosure. In some embodiments, the metallic surface is oxidized. The metallic surfaces modified according to the present disclosure may be of any shape, so long as there exists a metallic surface available to react with the phosphonic acid or phosphonate ester reagents described herein. In some embodiments, the metallic surface comprises platinum or an oxide thereof. In some embodiments, the metallic surface comprises gold or an oxide thereof. In some embodiments, the metallic surface comprises palladium or an oxide thereof. In some embodiments, the metallic comprises iridium or an oxide thereof. In some embodiments, the metallic surface comprises rhodium surface or an oxide thereof. In some embodiments, the metallic surface is a platinum surface, or an oxide thereof. In some embodiments, the metallic surface is a gold surface, or an oxide thereof. In some embodiments, the metallic surface is a palladium surface, or an oxide thereof. In some embodiments, the metallic surface is an iridium surface, or an oxide thereof. In some embodiments, the metallic surface is a rhodium surface, or an oxide thereof. In some embodiments, the metallic surface comprises silicon, aluminum, titanium, iron, zinc, zirconium, nickel, silver, copper, cobalt, or chromium. In some embodiments, the metallic surface is oxidized.

[0138] In some embodiments, the metallic surface is a planar metallic surface. In some embodiments, the metallic surface is a curved metallic surface. In some embodiments, the metallic surface has a 3D geometry. In some embodiments, the metallic surface is an electrode, a microchip, a bead, a microparticle, or a nanoparticle. In some embodiments, the metallic surface is an electrode. In some embodiments, the metallic surface is a microchip. In some embodiments, the metallic surface is a bead. In some embodiments, the metallic surface is a microparticle. In some embodiments, the metallic surface is a nanoparticle.

[0139] Any portion of the metallic surface may be modified with the surface modification provided herein. In some embodiments, at least about 1%, at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the metallic surface is functionalized. In some embodiments, at most about 1%, at most about 2%, at most about 5%, at most about 10%, at most about 20%, at most about 30%, at most about 40%, at most about 50%, at most about 60%, at most about 70%, at most about 80%, or at most about 90% of the metallic surface is functionalized. In some embodiments, about 1%, about 2%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, or substantially all of the metallic surface is functionalized. In some embodiments, the degree of surface functionalization is measured by the degree of coverage of the surface modification material over the surface. In some embodiments, the degree of surface functionalization is measured by the amount of phosphonate residues bound to the surface.

In some embodiments, the metallic surface is modified with the phosphonate at a concentration of about 0.0001 nmol/cm ² to about 5 nmol/cm ² . In some embodiments, the metallic surface is modified with the phosphonate at a concentration of about 0.0001 nmol/cm ² to about 0.001 nmol/cm ² , about 0.0001 nmol/cm ² to about 0.01 nmol/cm ² , about 0.0001 nmol/cm ² to about 0.05 nmol/cm ² , about 0.0001 nmol/cm ² to about 0.1 nmol/cm ² , about 0.0001 nmol/cm ² to about 0.5 nmol/cm ² , about 0.0001 nmol/cm ² to about 1 nmol/cm ² , about 0.0001 nmol/cm ² to about 1.5 nmol/cm ² , about 0.0001 nmol/cm ² to about 2 nmol/cm ² , about 0.0001 nmol/cm ² to about 5 nmol/cm ² , about 0.001 nmol/cm ² to about 0.01 nmol/cm ² , about 0.001 nmol/cm ² to about 0.05 nmol/cm ² , about 0.001 nmol/cm ² to about 0.1 nmol/cm ² , about 0.001 nmol/cm ² to about 0.5 nmol/cm ² , about 0.001 nmol/cm ² to about 1 nmol/cm ² , about 0.001 nmol/cm ² to about 1.5 nmol/cm ² , about 0.001 nmol/cm ² to about 2 nmol/cm ² , about 0.001 nmol/cm ² to about 5 nmol/cm ² , about 0.01 nmol/cm ² to about 0.05 nmol/cm ² , about 0.01 nmol/cm ² to about 0.1 nmol/cm ² , about 0.01 nmol/cm ² to about 0.5 nmol/cm ² , about 0.01 nmol/cm ² to about 1 nmol/cm ² , about 0.01 nmol/cm ² to about 1.5 nmol/cm ² , about 0.01 nmol/cm ² to about 2 nmol/cm ² , about 0.01 nmol/cm ² to about 5 nmol/cm ² , about 0.05 nmol/cm ² to about 0.1 nmol/cm ² , about 0.05 nmol/cm ² to about 0.5 nmol/cm ² , about 0.05 nmol/cm ² to about 1 nmol/cm ² , about 0.05 nmol/cm ² to about 1.5 nmol/cm ² , about 0.05 nmol/cm ² to about 2 nmol/cm ² , about 0.05 nmol/cm ² to about 5 nmol/cm ² , about 0.1 nmol/cm ² to about 0.5 nmol/cm ² , about 0.1 nmol/cm ² to about 1 nmol/cm ² , about 0.1 nmol/cm ² to about 1.5 nmol/cm ² , about 0.1 nmol/cm ² to about 2 nmol/cm ² , about 0.1 nmol/cm ² to about 5 nmol/cm ² , about 0.5 nmol/cm ² to about 1 nmol/cm ² , about 0.5 nmol/cm ² to about 1.5 nmol/cm ² , about 0.5 nmol/cm ² to about 2 nmol/cm ² , about 0.5 nmol/cm ² to about 5 nmol/cm ² , about 1 nmol/cm ² to about 1.5 nmol/cm ² , about 1 nmol/cm ² to about 2 nmol/cm ² , about 1 nmol/cm ² to about 5 nmol/cm ² , about 1.5 nmol/cm ² to about 2 nmol/cm ² , about 1.5 nmol/cm ² to about 5 nmol/cm ² , or about 2 nmol/cm ² to about 5 nmol/cm ² . In some embodiments, the metallic surface is modified with the phosphonate at a concentration of about 0.0001 nmol/cm ² , about 0.001 nmol/cm ² , about 0.01 nmol/cm ² , about 0.05 nmol/cm ² , about 0.1 nmol/cm ² , about 0.5 nmol/cm ² , about 1 nmol/cm ² , about 1.5 nmol/cm ² , about 2 nmol/cm ² , or about 5 nmol/cm ² . In some embodiments, the metallic surface is modified with the phosphonate at a concentration of at least about 0.0001 nmol/cm ² , about 0.001 nmol/cm ² , about 0.01 nmol/cm ² , about 0.05 nmol/cm ² , about 0.1 nmol/cm ² , about 0.5 nmol/cm ² , about 1 nmol/cm ² , about 1.5 nmol/cm ² , or about 2 nmol/cm ² . In some embodiments, the metallic surface is modified with the phosphonate at a concentration of at most about 0.001 nmol/cm ² , about 0.01 nmol/cm ² , about 0.05 nmol/cm ² , about 0.1 nmol/cm ² , about 0.5 nmol/cm ² , about 1 nmol/cm ² , about 1.5 nmol/cm ² , about 2 nmol/cm ² , or about 5 nmol/cm ² . In some embodiments, the metallic surface is modified with the phosphonate at concentration of about 0.01 nmol/cm ² to about 2 nmol/cm ² .

[0140] In some embodiments, the metallic surface is oxidized. In some embodiments, the metallic surface is oxidized to allow attachment of the phosphonate moiety of the surface modification provided herein. In some embodiments, the metallic surface is partially oxidized. In some embodiments, the metallic surface is fully oxidized. In some embodiments, a portion of the metallic surface is oxidized.

[0141] In some embodiments, at least about 1%, at least about 2%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, or at least about 90% of the metallic surface is oxidized. In some embodiments, at most about 1%, at most about 2%, at most about 5%, at most about 10%, at most about 20%, at most about 30%, at most about 40%, at most about 50%, at most about 60%, at most about 70%, at most about 80%, or at most about 90% of the metallic surface is oxidized. In some embodiments, about 1%, about 2%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, at most about 80%, about 90%, or substantially all of the metallic surface is oxidized. In some embodiments, the degree of oxidation of the metallic surface is measured by a percentage of the metal atoms on the metallic surface having an oxidation state greater than 0. In some embodiments, the degree of oxidation of the metallic surface is measured by the percentage of oxygen atoms covering the metallic surface.

[0142] In some embodiments, the metallic surface is an oxidized metal layer positioned on an exterior of a substrate. In some embodiments, the substrate is a metallic substrate. In some embodiments, the metallic substrate is an unoxidized metal. In some embodiments, the metallic substrate is the same metal as the oxidized metal layer. In some embodiments, the metallic substrate is the non-oxidized version of the oxidized metal layer. In some embodiments, the substrate is a different metal than the metallic surface. In some embodiments, the oxidized metal layer has a thickness of about 0.1 nm to about 10 nm. In some embodiments, the oxidized metal layer has a thickness of about 0.1 nm to about 0.2 nm, about 0.1 nm to about 0.5 nm, about 0.1 nm to about 1 nm, about 0.1 nm to about 5 nm, about 0.1 nm to about 10 nm, about 0.2 nm to about 0.5 nm, about 0.2 nm to about 1 nm, about 0.2 nm to about 5 nm, about 0.2 nm to about 10 nm, about 0.5 nm to about 1 nm, about 0.5 nm to about 5 nm, about 0.5 nm to about 10 nm, about 1 nm to about 5 nm, about 1 nm to about 10 nm, or about 5 nm to about 10 nm. In some embodiments, the oxidized metal layer has a thickness of about 0.1 nm, about 0.2 nm, about 0.5 nm, about 1 nm, about 5 nm, or about 10 nm. In some embodiments, the oxidized metal layer has a thickness of at least about 0.1 nm, about 0.2 nm, about 0.5 nm, about 1 nm, or about 5 nm. In some embodiments, the oxidized metal layer has a thickness of at most about 0.2 nm, about 0.5 nm, about 1 nm, about 5 nm, or about 10 nm. In some embodiments, the oxidized metal layer has a thickness of about 0.1 nm to about 1,000 nm. In some embodiments, the oxidized metal layer has a thickness of about 0.1 nm to about 0.5 nm, about 0.1 nm to about 1 nm, about 0.1 nm to about 5 nm, about 0.1 nm to about 10 nm, about 0.1 nm to about 50 nm, about 0.1 nm to about 100 nm, about 0.1 nm to about 500 nm, about 0.1 nm to about 1,000 nm, about 0.5 nm to about 1 nm, about 0.5 nm to about 5 nm, about 0.5 nm to about 10 nm, about 0.5 nm to about 50 nm, about 0.5 nm to about 100 nm, about 0.5 nm to about 500 nm, about 0.5 nm to about 1,000 nm, about 1 nm to about 5 nm, about 1 nm to about 10 nm, about 1 nm to about 50 nm, about 1 nm to about 100 nm, about 1 nm to about 500 nm, about 1 nm to about 1,000 nm, about 5 nm to about 10 nm, about 5 nm to about 50 nm, about 5 nm to about 100 nm, about 5 nm to about 500 nm, about 5 nm to about 1,000 nm, about 10 nm to about 50 nm, about 10 nm to about 100 nm, about 10 nm to about 500 nm, about 10 nm to about 1,000 nm, about 50 nm to about 100 nm, about 50 nm to about 500 nm, about 50 nm to about 1,000 nm, about 100 nm to about 500 nm, about 100 nm to about 1,000 nm, or about 500 nm to about 1,000 nm. In some embodiments, the oxidized metal layer has a thickness of about 0.1 nm, about 0.5 nm, about 1 nm, about 5 nm, about 10 nm, about 50 nm, about 100 nm, about 500 nm, or about 1,000 nm. In some embodiments, the oxidized metal layer has a thickness of at least about 0.1 nm, about 0.5 nm, about 1 nm, about 5 nm, about 10 nm, about 50 nm, about 100 nm, or about 500 nm. In some embodiments, the oxidized metal layer has a thickness of at most about 0.5 nm, about 1 nm, about 5 nm, about 10 nm, about 50 nm, about 100 nm, about 500 nm, or about 1,000 nm.

[0143] In some embodiments, the metallic surface comprises a mixture of metals. In some embodiments, the metallic surface comprises at least two metals selected from platinum, gold, palladium, titanium, and rhodium, or an oxide thereof. In some embodiments, the metallic surface comprises at least three metals selected from platinum, gold, palladium, titanium, and rhodium, or an oxide thereof.

[0144] In some embodiments, the metallic surface comprises at least one metal selected from platinum, gold, palladium, titanium, and rhodium, or an oxide thereof, and an additional material. In some embodiments, the additional material comprises an additional metal. In some embodiments, the additional material comprises an additional element.

[0145] In some embodiments, the metallic surface comprises platinum, or an oxide thereof, and an additional material. In some embodiments, the additional material comprises an additional metal. In some embodiments, the additional material comprises an additional element. In some embodiments, the metallic surface comprises platinum and the additional material comprises silicon, zirconium, gold, aluminum, titanium, iron, or zinc, or an oxide thereof, or any combination thereof. In some embodiments, the metallic surface comprises platinum and the additional material comprises silicon or zirconium.

[0146] In some embodiments, the metallic surface comprises gold, or an oxide thereof, and an additional material. In some embodiments, the additional material comprises an additional metal. In some embodiments, the additional material comprises an additional element. In some embodiments, the metallic surface comprises gold and the additional material comprises silicon, zirconium, platinum, aluminum, titanium, iron, or zinc, or an oxide thereof, or any combination thereof. In some embodiments, the metallic surface comprises gold and the additional material comprises silicon or zirconium.

[0147] In some embodiments, the metallic surface comprises palladium, or an oxide thereof, and an additional material. In some embodiments, the additional material comprises an additional metal. In some embodiments, the additional material comprises an additional element. In some embodiments, the metallic surface comprises palladium and the additional material comprises silicon, zirconium, gold, platinum, titanium, iron, or zinc, or an oxide thereof, or any combination thereof. In some embodiments, the metallic surface comprises palladium and the additional material comprises silicon or zirconium.

[0148] In some embodiments, the metallic surface comprises iridium, or an oxide thereof, and an additional material. In some embodiments, the additional material comprises an additional metal. In some embodiments, the additional material comprises an additional element. In some embodiments, the metallic surface comprises iridium and the additional material comprises silicon, zirconium, gold, aluminum, platinum, iron, or zinc, or an oxide thereof, or any combination thereof. In some embodiments, the metallic surface comprises iridium and the additional material comprises silicon or zirconium.

[0149] In some embodiments, the metallic surface comprises rhodium, or an oxide thereof, and an additional material. In some embodiments, the additional material comprises an additional metal. In some embodiments, the additional material comprises an additional element. In some embodiments, the metallic surface comprises rhodium and the additional material comprises silicon, zirconium, gold, aluminum, platinum, titanium, or zinc, or an oxide thereof, or any combination thereof. In some embodiments, the metallic surface comprises rhodium and the additional material comprises silicon or zirconium.

[0150] In some embodiments, the metallic surface comprises at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 98% of the metal by weight. In some embodiments, the metallic surface comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% of the metal by weight. In some embodiments, the metallic surface comprises at most about 50%, at most about 60%, at most about 70%, at most about 80%, at most about 90%, at most about 95%, or at most about 98% of the metal by weight.

[0151] In some embodiments, the metallic surface comprises at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 98% of the metal or any oxide thereof by weight. In some embodiments, the metallic surface comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% of the metal or any oxide thereof by weight. In some embodiments, the metallic surface comprises at most about 50%, at most about 60%, at most about 70%, at most about 80%, at most about 90%, at most about 95%, or at most about 98% of the metal or any oxide thereof by weight.

[0152] The metallic surfaces used herein may be substantially pure metals or alloys of different materials. In some embodiments, the metallic surface comprises a platinum alloy. The platinum may be alloyed with any other metal. In some embodiments, the platinum alloy comprises platinum alloyed with another metal, such as iron, nickel, copper, palladium, chromium, iridium, osmium, aluminum, tin, molybdenum, vanadium, niobium, tantalum, zirconium, manganese, ruthenium, gold, or cobalt. In some embodiments, the platinum alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% platinum by weight. In some embodiments, the platinum alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% platinum by weight.

[0153] In some embodiments, the metallic surface comprises a gold alloy. The gold may be alloyed with any other metal. In some embodiments, the gold alloy comprises gold alloyed with another metal, such as nickel, silver, palladium, platinum, rhodium, mercury, copper, zinc, aluminum, cadmium, manganese, gallium, indium, chromium, cobalt, iron, or ruthenium. In some embodiments, the gold alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% gold by weight. In some embodiments, the gold alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% gold by weight. [0154] In some embodiments, the metallic surface comprises a palladium alloy. The palladium may be alloyed with any other metal. In some embodiments, the palladium alloy comprises palladium alloyed with gold, platinum, iridium, rhodium, ruthenium, osmium, silver, nickel, copper, or manganese. In some embodiments, the palladium alloy comprises least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% palladium by weight. In some embodiments, the palladium alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% palladium by weight.

[0155] In some embodiments, the metallic surface comprises an iridium alloy. The iridium may be alloyed with any other metal. In some embodiments, the iridium alloy comprises iridium alloyed with platinum, ruthenium, osmium, nickel, cobalt, copper, titanium, or zirconium. In some embodiments, the iridium alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% iridium by weight. In some embodiments, the iridium alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% iridium by weight.

[0156] In some embodiments, the metallic surface comprises a rhodium alloy. The rhodium may be alloyed with any other metal. In some embodiments, the rhodium alloy comprises rhodium alloyed with platinum, molybdenum, iridium, ruthenium, palladium, osmium, titanium, rhenium, gold, or nickel. In some embodiments, the rhodium alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% rhodium by weight. In some embodiments, the rhodium alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% rhodium by weight.

[0157] In some embodiments, the metallic surface comprises an aluminum alloy. The aluminum may be alloyed with any other metal. In some embodiments, the aluminum alloy comprises aluminum alloyed with another metal, such as copper, magnesium, manganese, silicon, tin, zinc, iron, scandium, or zirconium. In some embodiments, the aluminum alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% aluminum by weight. In some embodiments, the aluminum alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% aluminum by weight.

[0158] In some embodiments, the metallic surface comprises a titanium alloy. The titanium may be alloyed with any other metal. In some embodiments, the titanium alloy comprises titanium alloyed with another metal, such as aluminum, vanadium, tin, niobium, iron, tantalum, zirconium, molybdenum, silicon, manganese, chromium, cobalt, nickel, or copper. In some embodiments, the titanium alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% titanium by weight. In some embodiments, the titanium alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% titanium by weight.

[0159] In some embodiments, the metallic surface comprises an iron alloy. The iron may be alloyed with any other metal or other element. In some embodiments, the iron is alloyed with another material, such as carbon, vanadium, chromium, niobium, titanium, nickel, cobalt, aluminum, manganese, uranium, silicon, or copper. In some embodiments, the iron alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% iron by weight. In some embodiments, the iron alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% iron by weight. In some embodiments, the iron alloy is steel.

[0160] In some embodiments, the metallic surface comprises a zinc alloy. The zinc may be alloyed with any other metal. In some embodiments, the zinc alloy comprises zinc alloyed with another metal, such as copper, tin, nickel, silver, mercury, magnesium, silicon, iron, lead, or aluminum. In some embodiments, the zinc iron alloy comprises at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 98% zinc by weight. In some embodiments, the zinc alloy comprises about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 98% zinc by weight.

[0161] The metallic surface may be functionalized with any number or combination of the surface modification, reactive groups, or capture moieties provided herein. In some embodiments, the metallic surface is functionalized with a single type of surface modification group, reactive group, or capture moiety. In some embodiments, the metallic surface is functionalized with a plurality of different surface modification groups, reactive groups, or capture moieties. In some embodiments, the metallic surface is modified by multiple copies of the same surface modification group, reactive group, or capture moiety.

II. USES OF MODIFIED METALLIC SURFACES

[0162] The metallic surfaces modified as provided herein may be used for any suitable purpose or configured to have any desired properties. Because of the wide range of moieties that can be bound to the metallic surfaces using the methods and reagents described herein, there is no limit to the application of such surfaces. Provided herein are non-limiting examples of potential uses of the modified metallic surfaces described herein.

[0163] Due to their conductive properties, metals such as gold and platinum are frequently used in electrodes, amongst other uses. Gold and platinum electrodes may be used in electrokinetic assays. However, the presence of the electric current in these assays can have deleterious electrochemistry effects on the samples, including but not limited to electrolysis reactions, heating, and chaotic fluid movement that may occur on or near the electrodes. In some embodiments, materials can be linked to metal electrode surfaces using the phosphonate bonds provided herein that can mitigate these effects, yet still allow the effective separation of cells, bacteria, virus, nanoparticles, DNA, and other biomolecules to be carried out. In some embodiments, a hydrogel is linked to the metal surface of the electrode in order prevent biological material from depositing on the electrode surface during an electrokinetic assay. In some embodiments, a hydrogel is linked to the metal surface of the electrode in order prevent biological material from becoming damaged or degraded during an electrokinetic assay. For this purpose, the hydrogel should have sufficient mechanical strength and be relatively chemically inert such that it will be able to endure the electrochemical effects at the electrode surface without disconfiguration or decomposition. In general, the hydrogel is sufficiently permeable to small aqueous ions, but keeps biomolecules away from the electrode surface.

[0164] In some embodiments, the metallic surface is configured to come into contact with a biological material. In some embodiments, the metallic surface is configured to come into contact with biological fluids (e.g. blood). In some embodiments, the metallic surface is modified with a phosphonate moiety provided herein in order to imbibe the metallic surface with anti-biofouling properties. In some embodiments, the metallic surfaces configured to come into contact with biological material comprise anti-biofouling coatings, such as hydrogels, hydrophilic polymers, or hydrophobic polymers.

[0165] The metallic surfaces modified herein may be configured to be placed inside the body of an animal. In some embodiments, the metallic surface is configured to be placed inside the body of a mammal. In some embodiments, the metallic surface is configured to be placed inside the body of a human. In some embodiments, the metallic surface is part of a medical implant. In some embodiments, the metallic surface is part of a surgical or dental implant. In some embodiments, the metallic surface is a surgical or dental implant. Such an implant may be modified with a phosphonate provided herein in order to prevent corrosion of the implant, prevent biofouling on the implant, prevent bacterial or other cell growth on the implant, or to alter any other desired surface property of the implant.

[0166] In some embodiments, the metallic surface comprises a material linked through the phosphonate moiety to prevent cell adhesion to the metallic surface. In some embodiments, the material is configured to prevent bacterial cell adhesion to the metallic surface. In some embodiments, the material comprises a polymer. In some embodiments, the polymer is grafted onto the metallic surface. In some embodiments, the polymer comprises quaternary ammonium ion- containing polymers (e.g. poly 2-dimethylaminoethyl methacrylate). In some embodiments, the polymer is poly 2-dimethylaminoethyl methacrylate. In some embodiments, the polymer is poly 4- vinyl pyridine. In some embodiments, the polymer is poly (3-(trimethoxysilyl)propyl methacrylate). In some embodiments, the polymer is a fluorocarbon of perfluorocarbon polymer. In some embodiments, the material comprises an antimicrobial peptide. In some embodiments, the material comprises a biocide chemically attached to the phosphonate. In some embodiments, the material linked through the phosphonate is used in conjunction with an additional anti-microbial treatment (e.g. surface treatment with an antiseptic such as chlorhexidine and/or chloroxylenol).

[0167] In some embodiments, the metallic surface comprises a material linked through the phosphonate moiety to prevent marine biofouling. In some embodiments, the material comprises a hydrophobic polymer. In some embodiments, the material comprises a silicone elastomer (e.g. polydimethylsiloxane). In some embodiments, the material comprises a mixture of silicone polymers. In some embodiments, the material comprises a hydrophobic polymer. In some embodiments, the hydrophobic polymer comprises polyethylene, polypropylene, polystyrene, polyvinylhalide, polytetrafluoroethylene, poly(methyl methacrylate), polycarbonate, polyether-urethane, polydimethylsiloxane, or any combination or derivative thereof. In some embodiments, the material comprises a fouling release coating.

[0168] In some embodiments, the metal phosphonate bonds provided herein may be used to immobilize drug moieties onto delivery devices with metallic surfaces. In some embodiments, the delivery devices are nanoparticles, microparticles, beads, or similar moieties having metallic surfaces. In one aspect, provided herein, is a drug delivery device comprising a drug moiety covalently linked to a surface of the device through a phosphonate residue, wherein the surface is platinum or gold. In some embodiments, the surface is platinum. In some embodiments, the surface is gold. In some embodiments, the surface is palladium, iridium, or rhodium. In some embodiments, the drug moiety is linked to the phosphonate residue through a linker. In some embodiments, the linker is a cleavable linker. In some embodiments, the linker is configured to release the drug moiety. The linker can be configured to release the drug moiety near a desired target, such as a tumor. In some embodiments, the drug delivery device further comprises a targeting moiety, such as an antibody or antibody fragment, a peptide, or a nucleic acid.

[0169] In some embodiments, the metal phosphonate provided herein may be used to prepare metallic surfaces useful in the purification of biological media. The phosphonate bonds to metallic surfaces may be used to link a plurality of binding agents to the surface. In some embodiments, the binding agents may bind a material of interest to the surface. In some embodiments, the biological media is washed over the surface, and materials of interest are bound to the surface. The biological media may then be removed from the surface. In some embodiments, the metallic surface is then washed to remove non-specifically bound materials from the surface. The material of interest may then be released from the metallic surface and recovered (e.g., by cleaving a linker between the binding agent and the surface or altering the properties of the binding agent, for example by denaturation). In some embodiments, the binding agents may be configured to bind material that is not of interest in order to remove it from the biological media. In some embodiments, the binding agents may be deployed on a metallic surface that can be easily removed from the media, such as a bead or microparticle. Such particles can be collected by a variety of methods (e.g. magnetic field or centrifugation). Collection of the particles with the undesired material bond can clarify a complex biological sample to leave behind only the material of interest.

[0170] In some embodiments, the metal phosphonate bonds provided herein may be used in the preparation of microarrays. The microarrays can be used for any purpose. In some embodiments, the microarrays can be used for DNA sequencing, protein expression analysis, protein-protein interaction screens, or any other biological assay capable of being performed in an array format. In some embodiments, the array comprises a plurality of features bound to a metallic surface through a phosphonate residue. In some embodiments, the features comprise probe moieties. In some embodiments, each feature comprises a unique probe moiety. In some embodiments, the probe moiety comprises a nucleic acid, a peptide, a protein, an antibody, a small molecule, a glycan, or any combination thereof. In some embodiments, the probe moieties comprise nucleic acids. In some embodiments, the nucleic acids comprise DNA or RNA. In some embodiments, the nucleic acids are single-stranded. In some embodiments, the nucleic acids comprise aptamers. In some embodiments, the microarray is configured for DNA sequencing. In some embodiments, the microarray is configured for expression analysis. In some embodiments, the expression analysis is protein expression analysis. In some embodiments, the probe moieties are configured to capture mRNA. In some embodiments, the probe moieties comprise peptides are proteins. In some embodiments, microarrays are configured for protein-protein interaction screens. The microarrays may have any number of features. In some embodiments, the microarray comprises at least 10, at least 100, at least 1000, at least 10000, or at least 100000 unique probe features.

III. METHODS OF MODIFYING METALLIC SURFACES

[0171] Also provided herein are methods of producing the modified metallic surfaces described herein. In some embodiments, metallic surfaces are able to be modified in a robust, reproducible fashion using a simple procedure. The simplicity of the methods provided herein allow for metallic surfaces to be modified with a high degree of control, which can be used to further functionalize the metallic surfaces in a reliable and consistent manner across batches.

[0172] In one aspect, provided herein is a method of functionalizing a metallic surface. In some embodiments, the method comprises depositing a phosphonic acid or phosphonate ester reagent on a metallic surface. In some embodiments, the method further comprises heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metallic surface. In some embodiments, the metallic surface is a platinum surface, or an oxide thereof. In some embodiments, the metallic surface is a gold surface, or an oxide thereof. In some embodiments, the metallic surface is a palladium, titanium, or rhodium, or an oxide thereof. In some embodiments, the metallic surface is oxidized.

[0173] In some embodiments, the phosphonic acid reagent comprises a phosphonic acid moiety. In some embodiments, the phosphonic acid reagent comprises a phosphonic acid derivative. In some embodiments, the phosphonic acid derivative is a phosphonate ester. In some embodiments, the phosphonate ester is an alkyl phosphonate ester. In some embodiments, the phosphonate ester is a methyl or ethyl ester. In some embodiments wherein the phosphonic acid reagent is a phosphonic acid derivative, the method further comprises adding an acid to the reaction mixture. In some embodiments, the acid is an organic acid (e.g. acetic acid, formic acid, and the like). In some embodiments, the acid is an inorganic acid (e.g. HC ₁ , HBr, H ₂ SO ₄ , and the like). In some embodiments, the acid is a strong acid. In some embodiments, the acid is a weak acid.

[0174] In some embodiments, depositing the phosphonic acid or phosphonate ester reagent comprises contacting the metallic surface with a solution comprising the phosphonic acid reagent. In some embodiments, depositing the phosphonic acid reagent comprises contacting the platinum surface with a solution comprising the phosphonic acid reagent and a solvent. Any solvent capable of dissolving the phosphonic acid reagent may be used. In some embodiments, the solvent comprises an organic solvent, an aqueous solvent, or any combination or mixture thereof. In some embodiments, the solvent is an organic solvent. In some embodiments, the organic solvent comprises acetic acid, acetone, acetonitrile, benzene, tert-butyl alcohol, tert- butyl methyl ether, carbon tetrachloride, chloroform, cyclohexane, 1,2-dichloroethane, di chi orom ethane, diethyl ether, diglyme, 1,2,- dimethoxyethane, dimethyl acetamide, dimethylformamide, dimethyl sulfoxide, dioxane, ethanol, ethyl acetate, ethyl methyl ketone, ethylene glycol, hexanes, hexamethylphosphoramide, methanol, nitromethane, pentanes, 2-proponal, pyridine, tetrahydrofuran, toluene, xylenes, or any combination thereof. In some embodiments, the organic solvent comprises ethanol, tetrahydrofuran, or toluene, or any combination thereof. In some embodiments, the organic solvent comprises ethanol, tetrahydrofuran, or toluene. In some embodiments, the organic solvent comprises ethanol. In some embodiments, the organic solvent comprises tetrahydrofuran. In some embodiments, the organic solvent comprises toluene.

[0175] The phosphonic acid or phosphonate ester reagent can be present in the solution at any concentration. In some embodiments, the reagent is present in the solution at a concentration of up to about 1 μM, 10 μM, 100 μM, 1 mM, 10 mM, 100 mM, or 1M. In some embodiments, the reagent is present in the solution at a concentration of about 1 μM, 10 μM, 100 μM, 1 mM, 10 mM, 100 mM, or 1 M. In some embodiments, the reagent is present in the solution at a concentration of at least about 1 μM, 10 μM, 100 μM, 1 mM, 10 mM, 100 mM, or 1 M. In some embodiments, the reagent is present in the solution at a concentration of about 1 mM. In some embodiments, the reagent is present in the solution at a concentration from about 1 μM, 10 μM, 100 μM, 1 mM, or 10 mM to about 10 μM, 100 μM, 1 mM, 10 mM, 100 mM, or 1 M. In some embodiments, the reagent is present in the solution at a concentration from about 1 μM to about 1 M.

[0176] In some embodiments, the depositing the reagent on the metallic surface comprises evaporating the solvent from the metallic surface. Any suitable method can be used to evaporate the solvent. In some embodiments, the solvent is allowed to evaporate under atmospheric pressure. In some embodiments, the solvent is evaporated using a vacuum source. In some embodiments, evaporating the solvent comprises heating the metallic surface. In some embodiments, the metallic surface is heated at a temperature of least 30°C, at least 40°C, at least 50°C, at least 60°C, at least 70°C, at least 80°C, or at least 90°C. In some embodiments, the metallic surface is heated at a temperature of about 30°C, about 40°C, about 50°C, about 60°C, about 70°C, about 80°C, or about 90°C.

[0177] In some embodiments, the metallic surface is heated to bind the phosphonic acid or phosphonate ester reagent with the metallic surface. Any method to heat the surface may be employed. In some embodiments, heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metallic surface occurs in an oven, a vacuum oven, or a microwave reactor. In some embodiments, heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metallic surface occurs in an oven. In some embodiments, heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metallic surface occurs in a vacuum oven. In some embodiments, heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metallic surface occurs in a microwave reactor.

[0178] In some embodiments, heating the metallic surface to bind the phosphonic acid or phosphonate ester reagent with the metallic surface comprises heating the metallic surface at a temperature of at least 30°C, at least 50°C, at least 70°C, at least 80°C, at least 100°C, at least 120°C, at least 140°C, at least 160°C, or at least 180°C. In some embodiments, heating the metallic surface to bind the reagent with the metallic surface comprises heating the metallic surface at a temperature of about 30°C, about 50°C, about 70°C, about 80°C, about 100°C, about 120°C, about 140°C, about 160°C, or about 180°C. In some embodiments, heating the metallic surface to bind the reagent with the metallic surface comprises heating the metallic surface at a temperature of at most 50°C, at most 70°C, at most 80°C, at most 100°C, at most 120°C, at most 140°C, at most 160°C, or at most 180°C.

[0179] In some embodiments, the metallic surface is oxidized. In some embodiments, the metallic surface is an oxidized metallic surface. In some embodiments, the metallic surface is partially oxidized. In some embodiments, the metallic surface is at least partially oxidized. In some embodiments, the metallic surface is fully oxidized.

[0180] In some embodiments, the method further comprises the step of oxidizing the metallic surface. Oxidizing the metallic surface may be accomplished using any method. In some embodiments, the metallic surface is oxidized by air oxidation, plasma treatment, ultraviolet-ozone oxidation, or chemical oxidation. In some embodiments, the metallic surface is oxidized by air oxidation. In some embodiments, the metallic surface is oxidized by ultraviolet-ozone oxidation. In some embodiments, the metallic surface is oxidized by plasma treatment. In some embodiments, the metallic surface is oxidized by chemical oxidation.

[0181] The phosphonic acid or phosphonate ester reagent may have any structure. In some embodiments, the phosphonic acid or phosphonate ester reagent has the structure wherein each R ^E is independently H or optionally substituted alkyl; and R is optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, or optionally substituted heteroaryl.

In some embodiments, each R ^E is independently H or optionally substituted C ₁ -C ₆ alkyl. In some embodiments, each R ^E is independently H or C ₁ -C ₆ alkyl. In some embodiments, each R ^E is independently H, methyl, ethyl, or propyl. In some embodiments, each R ^E is H. In some embodiments, each R ^E is independently methyl, ethyl, or propyl.

[0182] The R group of the phosphonic acid or phosphonate ester reagent can be any group. In some embodiments, R is optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted cycloalkyl, optionally substituted heterocycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, or optionally substituted heteroaryl. In some embodiments, R is any of the groups R as described in the "Modified Metallic Surfaces” section. In some embodiments, the phosphonic acid reagent is a phosphonate ester comprising any of the R groups as described in the "Modified Metallic Surfaces” section. In some embodiments, the phosphonate ester is an alkyl phosphonate ester. In some embodiments, the phosphonate ester is a C ₁ -C ₆ alkyl phosphonate ester. In some embodiments, the phosphonate ester is a methyl, ethyl, or propyl phosphonate ester.

[0183] In embodiments where the phosphonic acid or phosphonate ester reagent comprises a reactive tag or capture moiety, further groups may be added in order to further modify the properties the metallic surface. In some embodiments, the method further comprises adding a second group to the reagent by performing a further reaction. In some embodiments, further groups are added after attachment of the phosphonic acid or phosphonate ester reagent to the metallic surface. Any suitable reaction conditions that allows for the reaction of the reactive tag or capture moiety may be employed. In some embodiments, further groups are added by CLICK chemistry. In some embodiments, further groups are added by nucleophilic addition. In some embodiments, further groups are added by a polymerization reaction. In some embodiments, the polymerization reaction is atom-transfer radical- polymerization via (ATRP). In some embodiments, the polymerization reaction is reversible addition-fragmentation chain-transfer (RAFT) polymerization. In some embodiments, further groups are added by a cycloaddition reaction. In some embodiments, further groups are added by a conjugation reaction. In some embodiments, further groups are added by a bioconjugation reaction. The reactions used to add further groups may be employed in any solvent or solutions, such as an organic solvent, aqueous solution, or suitable buffer.

IV. DEFINITIONS

[0184] Unless defined otherwise, all terms of art, notations and other technical and scientific terms or terminology used herein are intended to have the same meaning as is commonly understood by one of ordinary skill in the art to which the claimed subject matter pertains. In some cases, terms with commonly understood meanings are defined herein for clarity and/or for ready reference, and the inclusion of such definitions herein should not necessarily be construed to represent a substantial difference over what is generally understood in the art.

[0185] Throughout this application, various embodiments may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range. [0186] As used in the specification and claims, the singular forms "a”, "an” and "the” include plural references unless the context clearly dictates otherwise. For example, the term "a sample” includes a plurality of samples, including mixtures thereof.

[0187] The terms "determining,” "measuring,” "evaluating,” "assessing,” " assaying,” and "analyzing” are often used interchangeably herein to refer to forms of measurement. The terms include determining if an element is present or not (for example, detection). These terms can include quantitative, qualitative or quantitative and qualitative determinations. Assessing can be relative or absolute. "Detecting the presence of’ can include determining the amount of something present in addition to determining whether it is present or absent depending on the context.

[0188] The terms " subject,” "individual,” or "patient” are often used interchangeably herein. A " subject” can be a biological entity containing expressed genetic materials. The biological entity can be a plant, animal, or microorganism, including, for example, bacteria, viruses, fungi, and protozoa. The subject can be tissues, cells and their progeny of a biological entity obtained in vivo or cultured in vitro. The subject can be a mammal. The mammal can be a human. The subject may be diagnosed or suspected of being at high risk for a disease. In some cases, the subject is not necessarily diagnosed or suspected of being at high risk for the disease.

[0189] As used herein, the term "about” a number refers to that number plus or minus 10% of that number. The term "about” a range refers to that range minus 10% of its lowest value and plus 10% of its greatest value.

[0190] "Alkyl" refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, which may optionally be unsaturated with one or more double or triple bonds. The alkyl is attached to the rest of the molecule by a single bond. Unless otherwise specified, the term "alkyl” and its equivalents encompass linear or branched alkyl groups. When an alkyl group is described as "linear,” the referenced alkyl group is not substituted with additional alkyl groups and is unbranched. When an alkyl group is described as " saturated,” the referenced alkyl group does not contain any double or triple carbon-carbon bonds (e.g. alkene or alkyne). The alkyl groups may be of any length, including, for example, one to fifteen carbon atoms (i.e., C ₁ -C ₁₅ alkyl), one to thirteen carbon atoms (i.e., C ₁ -C ₁₃ alkyl), one to eight carbon atoms (i.e., C ₁ -C ₈ alkyl), one to five carbon atoms (i.e., C ₁ -C ₅ alkyl), one to three carbon atoms (i.e., C ₁ -C ₃ alkyl), or one carbon atom (i.e., C ₁ alkyl). Additional lengths are also possible, such as up to twenty carbon atoms, up to thirty carbon atoms, up to fifty carbon atoms, or up to one hundred carbon atoms. In certain embodiments, the alkyl group is selected from methyl, ethyl, 1 -propyl («-propyl), 1 -methyl ethyl (iso-propyl), 1 -butyl (n-butyl), 1-methylpropyl (sec-butyl), 2-methylpropyl (iso-butyl), 1,1 -dimethyl ethyl (tert-butyl), 1 -pentyl (n-pentyl). [0191] "Alkenyl" refers to a straight or branched hydrocarbon chain radical group consisting solely of carbon and hydrogen atoms, containing at least one carbon-carbon double bond, and preferably having from two to twelve carbon atoms (i.e., C ₂ -C ₁₂ alkenyl). In certain embodiments, an alkenyl comprises two to ten carbon atoms (i.e., C ₂ -C ₁₀ alkenyl). In certain embodiments, an alkenyl comprises two to eight carbon atoms (i.e., C ₂ -C ₈ alkenyl). In other embodiments, an alkenyl comprises two to six carbon atoms (i.e., C ₂ -C ₆ alkenyl). The alkenyl may be attached to the rest of the molecule by a single bond, for example, ethenyl (i.e., vinyl), prop-1-enyl (i.e., allyl), but-1-enyl, pent-1-enyl, penta-1,4-dienyl, and the like.

[0192] "Alkynyl" refers to a straight or branched hydrocarbon chain radical group consisting solely of carbon and hydrogen atoms, containing at least one carbon-carbon triple bond, and preferably having from two to twelve carbon atoms (i.e., C ₂ -C ₁₂ alkynyl). In certain embodiments, an alkynyl comprises two to eight carbon atoms (i.e., C ₂ -C ₈ alkynyl). In other embodiments, an alkynyl comprises two to six carbon atoms (i.e., C ₂ -C ₆ alkynyl). In other embodiments, an alkynyl comprises two to four carbon atoms (i.e., C ₂ -C ₄ alkynyl). The alkynyl may be attached to the rest of the molecule by a single bond, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, and the like.

[0193] "Alkylene," "alkylene chain," or "alkyl chain " refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, which may optionally by unsaturated with one or more double or triple carbon-carbon bonds, and preferably having from one to twelve carbon atoms, for example, methylene, ethylene, propylene, n-butylene, and the like. The alkylene chain is attached to the rest of the molecule through a single bond and to the radical group through a single bond. The points of attachment of the alkylene chain to the rest of the molecule and to the radical group may be through any two carbons within the chain. In certain embodiments, an alkylene comprises one to ten carbon atoms (i.e., C ₁ -C ₈ alkylene). In certain embodiments, an alkylene comprises one to eight carbon atoms (i.e., C ₁ -C ₈ alkylene). In other embodiments, an alkylene comprises one to five carbon atoms (i.e., C ₁ -C ₅ alkylene). In other embodiments, an alkylene comprises one to four carbon atoms (i.e., C ₁ -C ₄ alkylene). In other embodiments, an alkylene comprises one to three carbon atoms (i.e., C ₁ -C ₃ alkylene). In other embodiments, an alkylene comprises one to two carbon atoms (i.e., C ₁ -C ₂ alkylene). In other embodiments, an alkylene comprises one carbon atom (i.e., Ci alkylene). In other embodiments, an alkylene comprises five to eight carbon atoms (i.e., C ₅ -C ₈ alkylene). In other embodiments, an alkylene comprises two to five carbon atoms (i.e., C ₂ -C ₅ alkylene). In other embodiments, an alkylene comprises three to five carbon atoms (i.e., C ₃ -C ₅ alkylene). [0194] " Alkenylene" or "alkenyl ene chain" refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing at least one carbon-carbon double bond, and preferably having from two to twelve carbon atoms. The alkenylene chain is attached to the rest of the molecule through a single bond and to the radical group through a single bond. The points of attachment of the alkenylene chain to the rest of the molecule and to the radical group may be through any two carbons within the chain. In certain embodiments, an alkenylene comprises two to ten carbon atoms (i.e., C ₂ -C ₁₀ alkenylene). In certain embodiments, an alkenylene comprises two to eight carbon atoms (i.e., C ₂ -C ₈ alkenylene). In other embodiments, an alkenylene comprises two to five carbon atoms (i.e., C ₂ -C ₅ alkenylene). In other embodiments, an alkenylene comprises two to four carbon atoms (i.e., C ₂ -C ₄ alkenylene). In other embodiments, an alkenylene comprises two to three carbon atoms (i.e., C ₂ -C ₃ alkenylene). In other embodiments, an alkenylene comprises two carbon atoms (i.e., C ₂ alkenylene). In other embodiments, an alkenylene comprises five to eight carbon atoms (i.e., C ₅ -C ₈ alkenylene). In other embodiments, an alkenylene comprises three to five carbon atoms (i.e., C ₃ -C ₅ alkenylene).

[0195] "Alkynylene" or "alkynylene chain" refers to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing at least one carbon-carbon triple bond, and preferably having from two to twelve carbon atoms. The alkynylene chain is attached to the rest of the molecule through a single bond and to the radical group through a single bond. The points of attachment of the alkynylene chain to the rest of the molecule and to the radical group may be through any two carbons within the chain. In certain embodiments, an alkynylene comprises two to ten carbon atoms (i.e., C ₂ -C ₁₀ alkynylene). In certain embodiments, an alkynylene comprises two to eight carbon atoms (i.e., C ₂ -C ₈ alkynylene). In other embodiments, an alkynylene comprises two to five carbon atoms (i.e., C ₂ -C ₅ alkynylene). In other embodiments, an alkynylene comprises two to four carbon atoms (i.e., C ₂ -C ₄ alkynylene). In other embodiments, an alkynylene comprises two to three carbon atoms (i.e., C ₂ -C ₃ alkynylene). In other embodiments, an alkynylene comprises two carbon atoms (i.e., C ₂ alkynylene). In other embodiments, an alkynylene comprises five to eight carbon atoms (i.e., C ₅ -C ₈ alkynylene). In other embodiments, an alkynylene comprises three to five carbon atoms (i.e., C ₃ -C ₅ alkynylene).

[0196] "Aryl" refers to an aromatic monocyclic or aromatic multicyclic hydrocarbon ring system. The aromatic monocyclic or aromatic multicyclic hydrocarbon ring system contains only hydrogen and carbon and from five to eighteen carbon atoms, where at least one of the rings in the ring system is aromatic, i.e., it contains a cyclic, delocalized (4n+2) π-electron system in accordance with the Hiickel theory. The ring system from which aryl groups are derived include, but are not limited to, groups such as benzene, fluorene, indane, indene, tetralin and naphthalene. [0197] "Aralkyl," "arylalkyl,” or "arylalkylene” refers to a radical of the formula -R ^c -aryl where R ^c is an alkylene chain as defined above, for example, methylene, ethylene, and the like. The alkylene chain part of the aralkyl radical is optionally substituted as described above for an alkylene chain.

[0198] "Aralkenyl" refers to a radical of the formula -R ^d -aryl where R ^d is an alkenylene chain as defined above. The aryl part of the aralkenyl radical is optionally substituted as described above for an aryl group.

[0199] "Aralkynyl" refers to a radical of the formula -R ^e -aryl, where R ^e is an alkynylene chain as defined above. The aryl part of the aralkynyl radical is optionally substituted as described above for an aryl group.

[0200] The term "C _x.y ” or "C _x -C _y ” when used in conjunction with a chemical moiety, such as alkyl, alkenyl, or alkynyl is meant to include groups that contain from x to y carbons in the chain. For example, the term " C _x.y alkyl” refers to saturated or unsaturated hydrocarbon groups, including straight-chain alkyl and branched-chain alkyl groups that contain from x to y carbons in the chain. The terms "C _x.y alkenyl” and "C _x.y alkynyl” refer to unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but that contain at least one double or triple bond respectively.

[0201] "Cycloalkyl" refers to a saturated ring in which each atom of the ring is carbon. Cycloalkyl may include monocyclic and polycyclic rings such as 3- to 10-membered monocyclic rings, 6- to 12- membered fused bicyclic rings, 6- to 12-membered spirocyclic rings, and 6- to 12-membered bridged rings. In certain embodiments, a cycloalkyl comprises three to ten carbon atoms. In other embodiments, a cycloalkyl comprises five to seven carbon atoms. The cycloalkyl may be attached to the rest of the molecule by a single bond. Examples of monocyclic cycloalkyls include, e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Polycyclic cycloalkyl radicals include, for example, adamantyl, norbomyl (z ^' .e., bicyclo[2.2.1]heptanyl), norbomenyl, decalinyl, 7,7-dimethyl-bicyclo[2.2.1]heptanyl, and the like. Unless otherwise specified (for example, when a "cycloalkyl” is described as " saturated”), a cycloalkyl group as described herein may contain one or more carbon-carbon double or triple bonds.

[0202] "Heteroalkyl" refers to a straight or branched hydrocarbon chain radical containing one or more heteroatoms. The heteroalkyl group may optionally be unsaturated with one or more double or triple bonds, either between adjacent carbon atoms, a carbon atom and a hetero atom, or between two heteroatoms. The heteroalkyl is attached to the rest of the molecule by a single bond. Unless otherwise specified, the term "heteroalkyl” and its equivalents encompass linear or branched alkyl groups. When a heteroalkyl group is described as "linear,” the referenced heteroalkyl group is not substituted with additional alkyl or heteroalkyl groups and is unbranched. When an heteroalkyl group is described as " saturated,” the referenced alkyl group does not contain any double or triple bonds (e.g. alkene or alkyne). The heteroalkyl groups may be of any length, including, for example, one to fifteen atom, one to thirteen atoms, one to eight atoms, one to five atoms, one to three atoms, or one to two atoms. Longer lengths are also possible, such as up to twenty atoms, up to thirty atoms, up to fifty atoms, or up to one hundred atoms.

[0203] "Heteroalkylene," "heteroalkylene chain," or "heteroalkyl chain” refers to a straight or branched divalent chain linking the rest of the molecule to a radical group, consisting of carbon , hydrogen, and one or more heteroatoms which may optionally by unsaturated with one or more double or triple carbon-carbon or carbon-heteroatom bonds. Exemplary heteroatoms include N, O, Si, P, B, and S atoms. The heteroalkylene chain is attached to the rest of the molecule through a single bond and to the radical group through a single bond. The points of attachment of the heteroalkylene chain to the rest of the molecule and to the radical group may be through any two atoms within the chain.

[0204] "Heterocycle” refers to a saturated, unsaturated or aromatic ring comprising carbon atoms and one or more heteroatoms. Exemplary heteroatoms include N, O, Si, P, B, and S atoms. Heterocycle may be monocyclic or polycyclic and may include 3- to 10-membered monocyclic rings, 6- to 12-membered fused bicyclic rings, 6- to 12-membered spirocyclic rings, and 6- to 12-membered bridged rings. Each ring of a bicyclic heterocycle may be selected from saturated, unsaturated, and aromatic rings. In some embodiments, the heterocycle is a heteroaryl. In some embodiments, the heterocycle is a heterocycloalkyl. In an exemplary embodiment, a heterocycle, e.g., pyridyl, may be fused to a saturated or unsaturated ring, e.g., cyclohexane, cyclopentane, or cyclohexene.

[0205] "Heterocycloalkyl" refers to a saturated ring with carbon atoms and at least one heteroatom. Exemplary heteroatoms include N, O, Si, P, B, and S atoms. Heterocycloalkyl may include monocyclic and polycyclic rings such as 3- to 10-membered monocyclic rings, 6- to 12- membered fused bicyclic rings, 6- to 12-membered spirocyclic rings, and 6- to 12-membered bridged rings. The heteroatoms in the heterocycloalkyl radical are optionally oxidized. One or more nitrogen atoms, if present, are optionally quaternized. The heterocycloalkyl is attached to the rest of the molecule through any atom of the heterocycloalkyl, valence permitting, such as any carbon or nitrogen atoms of the heterocycloalkyl. Examples of heterocycloalkyl radicals include, but are not limited to, dioxolanyl, thienyl[l,3]dithianyl, decahydroisoquinolyl, imidazolinyl, imidazolidinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, oxazolidinyl, piperidinyl, piperazinyl, 4-piperidonyl, pyrrolidinyl, pyrazolidinyl, quinuclidinyl, thiazolidinyl, tetrahydrofuryl, trithianyl, tetrahydropyranyl, thiomorpholinyl, thiamorpholinyl, 1-oxo-thiomorpholinyl, and 1, 1-dioxo-thiomorpholinyl.

[0206] "Heterocycloalkenyl" refers to a saturated ring with carbon atoms and at least one heteroatom and there is at least one double bond between two ring carbons. Exemplary heteroatoms include N, O, Si, P, B, and S atoms. Heterocycloalkenyl may include monocyclic and polycyclic rings such as 3- to 10-membered monocyclic rings, 6- to 12-membered fused bicyclic rings, 6- to 12- membered spirocyclic rings, and 6- to 12-membered bridged rings. In other embodiments, a heterocycloalkenyl comprises five to seven ring atoms. The heterocycloalkenyl may be attached to the rest of the molecule by a single bond. Examples of monocyclic cycloalkenyls include, e.g., pyrroline (dihydropyrrole), pyrazoline (dihydropyrazole), imidazoline (dihydroimidazole), triazoline (dihydrotriazole), dihydrofuran, dihydrothiophene, oxazoline (dihydrooxazole), isoxazoline (dihydroisoxazole), thiazoline (dihydrothiazole), isothiazoline (dihydroisothiazole), oxadiazoline (dihydrooxadiazole), thiadiazoline (dihydrothiadiazole), dihydropyridine, tetrahydropyridine, dihydropyridazine, tetrahydropyridazine, dihydropyrimidine, tetrahydropyrimidine, dihydropyrazine, tetrahydropyrazine, pyran, dihydropyran, thiopyran, dihydrothiopyran, dioxine, dihydrodioxine, oxazine, dihydrooxazine, thiazine, and dihydrothiazine.

[0207] "Heteroaryl" refers to an aromatic ring comprising carbon atoms and one or more heteroatoms. Exemplary heteroatoms include N, O, Si, P, B, and S atoms. As used herein, the heteroaryl ring may be selected from monocyclic or bicyclic and fused or bridged ring systems rings wherein at least one of the rings in the ring system is aromatic, i.e., it contains a cyclic, delocalized (4n+2) p-electron system in accordance with the Hiickel theory. The heteroatom(s) in the heteroaryl radical may be optionally oxidized. One or more nitrogen atoms, if present, are optionally quaternized. The heteroaryl may be attached to the rest of the molecule through any atom of the heteroaryl, valence permitting, such as a carbon or nitrogen atom of the heteroaryl. Examples of heteroaryls include, but are not limited to, azepinyl, acridinyl, benzimidazolyl, benzindolyl, 1,3-benzodioxolyl, benzofuranyl, benzooxazolyl, benzo[d]thiazolyl, benzothiadiazolyl, benzo[Z>][l,4]dioxepinyl, benzo[b][l,4]oxazinyl, 1,4-benzodioxanyl, benzonaphthofuranyl, benzoxazolyl, benzodioxolyl, benzodioxinyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, benzothienyl (benzothiophenyl), benzothieno[3,2-d]pyrimidinyl, benzotriazolyl, benzo[4,6]imidazo[l,2-a]pyridinyl, carbazolyl, cinnolinyl, cyclopenta[d]pyrimidinyl, 6,7-dihydro-5H-cyclopenta[4,5]thieno[2,3-d]pyrimidinyl, 5,6-dihydrobenzo[h]quinazolinyl,

5,6-dihydrobenzo[h]cinnolinyl, 6,7-dihydro-5H-benzo[6,7]cyclohepta[l,2-c]pyridazinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, furanonyl, furo[3,2-c]pyridinyl, 5,6,7,8,9,10-hexahydrocycloocta[d]pyrimidinyl, 5,6,7,8,9,10-hexahydrocycloocta[d]pyridazinyl, 5,6,7,8,9,10-hexahydrocycloocta[d]pyridinyl, isothiazolyl, imidazolyl, indazolyl, indolyl, indazolyl, isoindolyl, indolinyl, isoindolinyl, isoquinolyl, indolizinyl, isoxazolyl,

5.8-methano-5,6,7,8-tetrahydroquinazolinyl, naphthyridinyl, 1,6-naphthyridinonyl, oxadiazolyl,

2-oxoazepinyl, oxazolyl, oxiranyl, 5,6,6a,7,8,9,10,10a-octahydrobenzo[h]quinazolinyl, 1 -phenyl- liT-pyrrolyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyrazolo[3,4-d]pyrimidinyl, pyridinyl, pyrido[3,2-d]pyrimidinyl, pyrido[3,4-d]pyrimidinyl, pyrazinyl, pyrimidinyl, pyridazinyl, pyrrolyl, quinazolinyl, quinoxalinyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, 5,6,7,8-tetrahydroquinazolinyl,

5.6.7.8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidinyl,

6.7.8.9-tetrahydro-5H-cyclohepta[4,5]thieno[2,3-d]pyrimid inyl,

5,6,7,8-tetrahydropyrido[4,5-c]pyridazinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, thieno[2,3-d]pyrimidinyl, thieno[3,2-d]pyrimidinyl, thieno[2,3-c]pridinyl, and thiophenyl ( i.e . thienyl).

[0208] The term " substituted” refers to moieties having substituents replacing a hydrogen on one or more carbons or heteroatoms of the structure. It will be understood that " substitution” or " substituted with” includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. As used herein, the term " substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this disclosure, the heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. When a specified group is described as "optionally substituted,” it is intended that the group may or may not contain a substituent. In embodiments where it is unspecified whether a group is substituted or unsubstituted, it is intended that the group is optionally substituted. Unless otherwise specified, the substituents described herein may themselves be further substituted with their own substituents, with each of these substituents being further optionally substituted.

[0209] Substituents can include any substituents described herein, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, an aralkyl, a carbocycle, a heterocycle, a cycloalkyl, a heterocycloalkyl, an aromatic and heteroaromatic moiety. In some embodiments, substituents may include any substituents described herein, for example: halogen, hydroxy, oxo (=0), thioxo (=S), cyano (-CN), nitro (-NO2), imino (=N-H), oximo (=N-OH), hydrazino (=N-NH ₂ ), -R ^b -OR ^a , -R ^b -OC(O)-R ^a , -R ^b -OC(O)-OR ^a , -R ^b -OC(O)-N(R ^a ) ₂ , -R ^b -N(R ^a ) ₂ , - R ^b -C(O)R ^a , -R ^b -C(O)0R ^a , -R ^b -C(O)N(R ^a ) ₂ , -R ^b -O-R ^c -C(O)N(R ^a ) ₂ , -R ^b -N(R ^a )C(O)0R ^a , -

R ^b -N(R ^a )C(O)R ^a , -R ^b -N(R ^a )S(O) _t R ^a (where t is 1 or 2), -R ^b -S(O) _t R ^a (where t is 1 or 2), -R ^b -S(O) _t 0R ^a (where t is 1 or 2), and -R ^b -S(O) _t N(R ^a ) ₂ (where t is 1 or 2); and alkyl, alkenyl, alkynyl, aryl, aralkyl, aralkenyl, aralkynyl, cycloalkyl, cycloalkylalkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl, and heteroarylalkyl any of which may be optionally substituted by alkyl, alkenyl, alkynyl, halogen, hydroxy, haloalkyl, haloalkenyl, haloalkynyl, oxo (=0), thioxo (=S), cyano (-CN), nitro (- N0 ₂ ), imino (=N-H), oximo (=N-OH), hydrazine (=N-NH ₂ ), -R ^b -OR ^a , -R ^b -OC(O)-R ^a , - R ^b -OC(O)-OR ^a , -R ^b -OC(O)-N(R ^a ) ₂ , -R ^b -N(R ^a ) ₂ , -R ^b -C(O)R ^a , -R ^b -C(O)0R ^a , -R ^b -C(O)N(R ^a ) ₂ , - R ^b -O-R ^c -C(O)N(R ^a ) ₂ , -R ^b -N(R ^a )C(O)0R ^a , -R ^b -N(R ^a )C(O)R ^a , -R ^b -N(R ^a )S(O) _t R ^a (where t is 1 or 2), -R ^b -S(O) _t R ^a (where t is 1 or 2), -R ^b -S(O) _t 0R ^a (where t is 1 or 2) and -R ^b -S(O) _t N(R ^a ) ₂ (where t is 1 or 2); wherein each R ^a is independently selected from hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocycloalkyl, heterocycloalkylalkyl, heteroaryl, or heteroarylalkyl, wherein each R ^a , valence permitting, may be optionally substituted with alkyl, alkenyl, alkynyl, halogen, haloalkyl, haloalkenyl, haloalkynyl, oxo (=0), thioxo (=S), cyano (-CN), nitro (-N0 ₂ ), imino (=N-H), oximo (=N-OH), hydrazine (=N-

NH ₂ ), -R ^b -OR ^a , -R ^b -OC(O)-R ^a , -R ^b -OC(O)-OR ^a , -R ^b -OC(O)-N(R ^a ) ₂ , -R ^b -N(R ^a ) ₂ , -R ^b -C(O)R ^a , -R ^b -C (O)0R ^a , -R ^b -C(O)N(R ^a ) ₂ , -R ^b -O-R ^c -C(O)N(R ^a ) ₂ , -R ^b -N(R ^a )C(O)0R ^a , -R ^b -N(R ^a )C(O)R ^a , -R ^b -N(R ^a ) S(O) _t R ^a (where t is 1 or 2), -R ^b -S(O) _t R ^a (where t is 1 or 2), -R ^b -S(O) _t 0R ^a (where t is 1 or 2) and -R ^b -S(O) _t N(R ^a ) ₂ (where t is 1 or 2); and wherein each R ^b is independently selected from a direct bond or a straight or branched alkylene, alkenylene, or alkynylene chain, and each R ^c is a straight or branched alkylene, alkenylene or alkynylene chain.

[0210] Unless otherwise specified, it is intended that any group bearing multiple points of attachment to a parent molecule or to two or more moieties can be oriented in any direction. For example, for a structure of Formula A-B-C, wherein B is it is intended that both and are encompassed.

[0211] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. V. EXAMPLES

[0212] The following examples are included for illustrative purposes only and are not intended to limit the scope of the invention.

Example 1: Platinum Surface Functionalization with (ll-((2-BROMO-2-

METHYLPROPANOYL)OXY)UNDECYL)PHOSPHONIC ACID

[0213] A variety of conditions for functionalizing a platinum surface were attempted in order to attach a phosphonic acid reagent to the platinum surface. The reagent (11-((2-BROMO-2- METHYLPROPANOYL)OXY)UNDECYL)PHOSPHONIC ACID (BMPOUA) was selected because it contains the 2-bromo-2-methylpropanoyl moiety to allow for further functionalization of the platinum surface after attachment of the phosphonic acid moiety directly to the surface.

[0214] In initial experiments, the protocol depicted in FIG.2 was utilized. Briefly, 40 mg of BMPOUA was dissolved in 100 mL tetrahydrofuran (THF). Platinum chip was then added to the THF solution. The THF solution was then heated at 60°C and the THF allowed to evaporate. The chips were placed in an oven at 140°C for 2 days to anneal the phosphonic acid to the surface. Chips were then rinsed with methanol and dried.

[0215] In order to assess the effectiveness of the reaction conditions above for attaching the phosphonic acid reagent to the surface, it was attempted to link the 2-bromo-2-methylpropanoyl moiety of the resulting metal phosphonate with a suitable acrylate reagent in a radical polymerization reaction. If the platinum surface was successfully modified with BMPOUA, a polymer should "grow” on the platinum surface under the reaction conditions. Polymer growth was observed on the chips, but with substantial variability from chip to chip.

Next effects of solvent on the reaction were studied. A solution of 1 mM phosphonic acid was prepared using THF, ethanol (EtOH), or toluene as the solvent. A platinum chip was then soaked in the mixture with no mixing at 60°C. The reactions were run for 22 hours and worked up with a variety of ways, including evaporating the reaction solvent, removing the platinum chip from the solvent and rinsing with methanol, and removing the platinum from the chip and placing directly into a vacuum oven at 140°C overnight. Following these surface modification protocols, a suitable acrylate reagent was attempted to grow a polymer on the surface of chip. EtOH was found to be the most robust solvent for the surface functionalization reaction as it showed the most consistent amount of polymer growth following the initial surface functionalization.

Example 2: Effect of Pt Surface Oxidation on Functionalization

[0216] It was suspected that the presence of -OH groups on the platinum surface played a role in the covalent attachment of the phosphonic acid. In order to assess the role of platinum oxidation state in covalent bond formation with phosphonic acids, platinum chips were subjected to plasma treatment (high energy O2 plasma reactive ion etching) to oxidize portions of the platinum surface, treatment with a post-etch removal reagent (for example, EKC4000® from DuPont) to remove any oxidized platinum, or the platinum chips were not subject to any treatment prior to reaction with phosphonic acid reagent.

[0217] Plasma treated and untreated platinum chips were analyzed by X-ray photoelectron spectroscopy (XPS) in order to assess the oxidation state of the chips. Atomic composition and chemical state information was obtained on a PHI Quantum 2000 using the following parameters: X- ray source: Monochromated Alk _α 1486.6eV; Acceptance Angle: ±23°; Take-off Angle: 45°; Analysis area: 600μm diameter; Charge Correction: Cls 284.8eV (C-C, C-H). Chemical state assignments for a given element were made by consulting reference data from the literature. Non-linear least squares (NLLS) curve fitting was applied to assist in chemical state assignment.

[0218] XPS measurements of the oxidized and untreated platinum chips are shown in FIG. 3A and FIG. 3B. FIG. 3A shows a survey scan of the surfaces of three chips. Chips 1 and 2 were subjected to plasma treatment, and Chip 3 was untreated. FIG. 3B shows an XPS assessment of the various oxidation states of platinum on the chip. The data indicates that the platinum existed in various oxidation states on each chip. The relative proportion of platinum in each oxidation state (Pt ₀ , Pt ²⁺ , Pt ⁴⁺ ) for the oxidized platinum and non-plasma treated chips is shown in Table 1 below. For the untreated chip, most of the platinum was in an unoxidized state. In contrast, the plasma treated platinum chips showed elevated levels of oxidized platinum.

Table 1

[0219] Following assessment of platinum chips for oxidation levels, the surfaces were subject to a functionalization reaction with BMPOUA. In a round bottom flask, BMPOUA (Millipore Sigma) was dissolved in ethanol (Millipore Sigma) at a concentration of 1.2 mM. After mixing at room temperature for 5 minutes the solution was poured into a reaction vessel and the platinum metal substrate (plasma treated, untreated, or post-etch removal reagent treated) was submerged in the phosphonic acid solution without stirring. The reaction vessel was flushed with ultra-high purity argon gas (Airgas) for 5 minutes, and the platinum substrate remained submerged for 18 hours at room temperature. Following completion, the substrate was removed from the ethanol solution and placed directly into an oven (VWR Gravity Convection Oven) without washing at 140 C for 2 hours to allow the BMPOUA to anneal to the substrate. [0220] In order to assess the amount of BMPOUA annealed to the platinum substrate, the materials were subject to a polymerization reaction with an acrylate reagent. If the platinum surface was successfully modified with BMPOUA, a polymer should "grow” on the platinum surface under the reaction conditions. The more BMPOUA that is bound to the surface of the platinum substrate, the more polymer will be present bound to the chip following the reaction. Following the polymerization reactions on the modified surfaces of the plasma treated, untreated, and post-etch removal reagent treated surfaces, surface roughness measurements were obtained by an optical profilometer (Profilm 3D, Filmetrics F40 microscope) using a normal scan speed (Backscan = 0 mm, Scan Length = 0.02 mm, Scan Averages = 4). Images were obtained in PSI mode using a 50x DI (Nikon) at 4x zoom. Following image acquisition, a Spline filter (Gaussian β = 0.625242, Cuttoff Length = 8 μm) was applied. Resulting mean polymer hydrogel thickness measurements are shown below in Table 2 for the plasma treated and untreated chips. The post-etch removal reagent treated platinum chips did not display any observable polymer growth. Comparing the coefficient of variation and mean thickness, the more oxidized surface results in a more uniform polymer (Oxidized Pt CV% = 6.1 vs Unoxidized Pt CV% = 11.0) and thicker polymer (oxidized Pt polymer mean thickness = 33.1 nm vs unoxidized Pt polymer mean thickness = 26.1 nm). In addition, the ability of the functionalized platinum substrates to conduct current was assessed. As expected, the untreated metallic substrate displayed higher current measurements (108.4 mAmps) relative to the more oxidized plasma treated substrate (mean = 99.2 mAmps).

Table 2

Example 3: Characterization of Modified Platinum Surfaces

[0221] Multiple platinum chips were functionalized with BMPOUA and characterized using a variety of techniques. The protocol for the functionalization was as follows: In a round bottom flask, BMPOUA (Millipore Sigma) was dissolved in ethanol (Millipore Sigma) at a concentration of 1.2 mM. After mixing at room temperature for 5 minutes the solution was poured into a reaction vessel and the platinum metal substrate (plasma treated, untreated, or post-etch removal reagent treated) was submerged in the phosphonic acid solution without stirring. The reaction vessel was flushed with ultra-high purity argon gas (Airgas) for 5 minutes, and the platinum substrate remained submerged for 18 hours at room temperature. Following completion, the substrate was removed from the ethanol solution and placed directly into an oven (VWR Gravity Convection Oven) without washing at 140 C for 2 hours to allow the BMPOUA to anneal to the substrate. [0222] Following reaction with BMPOUA, evidence of platinum metal functionalization with the phosphonic acid was observed by measuring Arithmetic mean height (Sa) both before and after functionalization. This was accomplished using an optical profilometer (Profilm3D, Filmetrics). Surface roughness measurements were obtained using a normal scan speed (Backscan = 0 mm, Scan Length = 0.02 mm, Scan Averages = 4). Images were obtained in PSI mode using a 50x DI (Nikon) at 4x zoom. Following image acquisition, the image was cropped so that only the platinum electrode was considered and a Spline filter (Gaussian β = 0.625242, Cutoff Length = 8 μm) was applied. As shown in Table 3, when the platinum metal is treated with the phosphonic acid, surface roughness values increase by 70% (Sa = 0.94 nm vs 1.71 nm for bare Pt metal and treated Pt metal, respectively). This change in roughness can be attributed to the covalent binding of the phosphonic acid to the platinum metal.

Table 3

[0223] FIG. 4 shows an image of a bare platinum electrode before surface functionalization. In the platinum electrode of FIG. 4, the arithmetic mean height (Sa) before functionalization is 0.763 nm. FIG. 5 shows the same platinum electrode following functionalization with BMPOUA phosphonic acid reagent as described above. The Sa electrode after functionalization increased to 2.328 nm, consistent with successful attachment of the reagent.

[0224] After successful attachment of phosphonic acid derivative BMPOUA, the platinum electrode surface bearing the functionality was subject to radical polymerization conditions in the presence of a suitable acrylate reagent. Upon completion of this reaction, the surface of the platinum electrode was analyzed by scanning electron microscopy (SEM), as were platinum electrodes not subject to any derivatization. Images were obtained using a FEI Quanta 250 SEM at a standard working distance of 10 mm. Accelerating voltage was typically set to 3-5 keV and beam current at 0.1 nA. All images were obtained using a standard electron detector (ETD) and the stage was titled to varying degrees as indicated in FIGs. 6A, 6B, and 7-14

[0225] FIG. 6A shows an SEM image of a bare platinum electrode surrounded by dielectric at a tilt angle of 45°. Both the platinum metal surface and dielectric appear smooth. FIG. 6B, by comparison, shows a platinum electrode functionalized with BMPOUA followed by a polymerization reaction similarly surrounded by a dielectric material. After running electric current through the electrode in FIG. 6B, polymer "folding” is observed at the edge of the modified platinum surface near the interface of the dielectric material.

[0226] FIGs 7-10 show additional SEM images of polymer functionalized platinum electrodes. FIG. 7 shows an SEM image taken from a 0° tilt angle. Folded polymer can be seen on the platinum surface. FIG. 8 shows an SEM image taken a 14° tilt angle. Polymer folding near the interface of the platinum surface and the dielectric layer can be clearly seen. FIG. 9 shows a similar SEM image at a tilt angle of 14°. The region captured is the same as FIG. 8, but with a broader view. FIG. 10 shows an additional SEM image at a tilt angle of 14° from a further zoomed out view.

[0227] FIGs 11-14 show SEM images of unfunctionalized platinum electrodes surrounded by a dielectric material. Notably, all of the images show a smooth surface as compared to the functionalized platinum surfaces shown in FIGs 7-10. FIG. 11 shows an SEM image at a tilt angle of 1°. The left side of the image shows the platinum surface with a dielectric material at the right side. FIG. 12 shows a SEM image of the same electrode at a 45° tilt angle. The interface of the platinum surface and dielectric material appears smooth. FIG. 13 shows an SEM image at a 4° tilt angle in a zoomed-out view of the electrode. FIG. 14 shows a close-up image of the smooth platinum surface boundary with the dielectric material at an angle of 45°.

[0228] While preferred embodiments of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the disclosure. It should be understood that various alternatives to the embodiments of the disclosure described herein may be employed in practicing the disclosure. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.